Thomas Kvist
Editor
Apical Periodontitis
in Root-Filled Teeth
Endodontic Retreatment
and Alternative Approaches
123
Apical Periodontitis in Root-Filled Teeth
Thomas Kvist
Editor
Apical Periodontitis in
Root-Filled Teeth
Endodontic Retreatment and
Alternative Approaches
Editor
Thomas Kvist
Department of Endodontology
University of Gothenburg The Sahlgrenska Academy
Gothenburg
Sweden
ISBN 978-3-319-57248-2 ISBN 978-3-319-57250-5
https://doi.org/10.1007/978-3-319-57250-5
(eBook)
Library of Congress Control Number: 2017957215
© Springer International Publishing AG 2018
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Contents
1Introduction�������������������������������������������������������������������������������������� 1
Thomas Kvist
2Incidence, Frequency, and Prevalence ������������������������������������������ 7
Fredrik Frisk
3Aetiology of Persistent Endodontic Infections
in Root-Filled Teeth������������������������������������������������������������������������� 21
Luis E. Chávez de Paz
4Consequences������������������������������������������������������������������������������������ 33
Fredrik Frisk and Thomas Kvist
5Diagnosis ������������������������������������������������������������������������������������������ 43
Thomas Kvist and Peter Jonasson
6Decision Making������������������������������������������������������������������������������ 55
Thomas Kvist
7Surgical Retreatment���������������������������������������������������������������������� 73
Peter Jonasson and Magnús Friðjón Ragnarsson
8Non-surgical Retreatment �������������������������������������������������������������� 89
Charlotte Ulin
9Prognosis ���������������������������������������������������������������������������������������� 103
Thomas Kvist
10Alternatives: Extraction and Tooth Replacement���������������������� 117
Pernilla Holmberg
Index�������������������������������������������������������������������������������������������������������� 133
v
List of Contributors
Luis E. Chávez de Paz, DDS, MS, PhD Division of Endodontics,
Department of Dental Medicine, Karolinska Institute, Huddinge, Sweden
Fredrik Frisk, DDS, PhD Department of Endodontology, Institute for
Postgraduate Dental Education, Jönköping, Sweden
Department of Endodontology, Institute of Odontology, University of
Gothenburg, The Sahlgrenska Academy, Göteborg, Sweden
Pernilla Holmberg, DDS Department of Oral Prosthodontics and National
Oral Disability Centre, Institute for Postgraduate Dental Education,
Jönköping, Sweden
Peter Jonasson, DDS, PhD Department of Endodontology, Institute of
Odontology, The Sahlgrenska Academy, University of Gothenburg, Göteborg,
Sweden
Thomas Kvist, DDS, PhD Department of Endodontology, Institute of
Odontology, The Sahlgrenska Academy, University of Gothenburg, Göteborg,
Sweden
Magnús Friðjón Ragnarsson, DDS Endodontist in private practice,
Reykjavik, Iceland
Charlotte Ulin, DDS Specialist Clinic of Endodontics, Public Dental
Service Västra Götaland, Göteborg, Sweden
vii
1
Introduction
Thomas Kvist
Our discussion will be adequate if it has as much clearness as the subject-matter admits
of, for precision is not to be sought for alike in all discussions,… for it is the mark of an
educated man to look for precision in each class of things just so far as the nature of the
subject admits.
Aristotle (350 BC) Nicomachean Ethics. Translated by W D Ross
Abstract
Diagnosis and treatment of the pathological conditions of the dental pulp
and the periradicular tissues is the primary focus of Endodontology. Over
more than 100 years, clinical experience and scientific research have generated a substantial base of critical knowledge. Reports published in journals and textbooks have indeed established the principles for endodontic
therapy. As a consequence, endodontics has become a well-established
and natural branch of restorative dentistry. Billions of teeth are saved from
extraction. However, the powerful diagnostic and treatment potential characterizing endodontology, today has resulted in new clinical, scientific and
ethical challanges.
1.1
Contemporary Endodontics
Diagnosis and treatment of the pathological conditions of the dental pulp and the periradicular
tissues is the primary focus of Endodontology.
Over more than 100 years, clinical experience
and scientific research have generated a substantial base of critical knowledge. Reports
published in journals and textbooks have
indeed established the principles for endodontic therapy. As a consequence, endodontics has
become a well-­established and natural branch of
T. Kvist, PhD, DDS
Department of Endodontology, Institute of
Odontology, The Sahlgrenska Academy,
University of Gothenburg, Göteborg, Sweden
e-mail: kvist@odontologi.gu.se
© Springer International Publishing AG 2018
T. Kvist (ed.), Apical Periodontitis in Root-Filled Teeth,
https://doi.org/10.1007/978-3-319-57250-5_1
restorative dentistry. Billions of teeth are saved
from extraction and dentistry, at least in developed countries, has abandoned the “Pull and be
Damned Road” [1].
The advancement of new instruments and techniques for diagnosis and treatment in endodontics has been a predominant feature of research
and development over the past 25 years. By virtue of the strong technological expansion in the
discipline, endodontic therapy is currently a very
feasible and attractive discipline that allows the
prudent and skillful endodontists and many general dental practitioners to properly manage most
teeth in need of endodontic treatment.
However, in a “globalized world,” the powerful diagnostic and treatment potential characterizing endodontics, as well as most other disciplines
in medicine and dentistry, today have resulted in
new clinical, scientific, and ethical challenges.
1
T. Kvist
2
1.2
he Continued High
T
Prevalence of Caries
in a Growing and Aging
Population
For most of the twentieth century, the incidence
of dental caries declined in many developed
countries, but from a worldwide perspective,
dental caries remains the most prevalent human
ailment. In 2010 it was calculated that 2.4 billion
people were affected by untreated caries in the
permanent dentition. At the same time, the global
population is growing and the life expectancy is
increasing while tooth loss is decreasing.
Consequently, the need for “saving teeth” by
endodontic therapy is inexhaustible in the foreseeable future [2].
In many countries, people keep their teeth longer, and with increasing age, the prevalence of
the number of teeth in need of endodontic treatment increases [3]. At the same time, the medical
and technical challenges and d­ ifficulties may be
very extensive for the c­ linician [4].
1.3
he Increasing Costs
T
and Fair Distribution
of High-Quality Dental Care
Modern endodontics is associated with seemingly constant pressure in increasing cost of
delivering endodontic care. During my practice
lifetime, 30 years, I have seen the necessary
armamentarium for root canal treatment go
from some hand files, gutta-percha, chloroform, a few spreaders, and analog X-rays to
ever more expensive technology like microscopes, Ni-Ti machine driven instruments,
ultrasonics, apexlocators, and CBCT imaging
equipment. Whatever new technology the
future brings, it is unlikely to reduce the cost of
delivering care. So, one of the big challenges
in the future will be staying current with technological innovations and scientific development while keeping costs low enough for poor,
retired, disabled, low, or flat income people to
be able to keep teeth that are in need of endodontic procedures. If not, fewer people can
afford the cost of high-quality dental care,
including preventive measures. Saving teeth by
endodontic treatment risks to become a privilege only for a few [5].
1.4
he Lack of Solid Evidence
T
for Many Methods
of Diagnostic and Treatment
Procedures in Endodontics
Several careful analyses of the evidence basis for
the methods that we apply in endodontics have
demonstrated extensive shortcomings. The situation is worrying for diagnostic and treatment
procedures as well as for evaluation of the results
of our methods [6]. This is not least when it
comes to the presence of apical lesions in rootfilled teeth.
1.5
he Importance of Technical
T
Skills and Good Clinical
Judgment
Endodontics is not only about applying best scientific evidence to clinical practice. As a matter of fact, the operator’s clinical expertise and
patient’s preferences in any clinical situation are
equally important. There are different forms of
skills a good clinician must acquire. The technical skill a clinician must gain in order to render
proper treatments can only partially be gained
from research or “reading.” Therefore, practical training on models, careful implementation
of new clinical methods and watching skillful
colleagues at work, and reflecting on what has
been learned are consistently important for the
development of a skillful endodontist. The clinical situation also demands that dentists exercise
good clinical judgment. This means “to do the
right thing at the right moment.” In the tradition
of the works of the Greek philosopher Aristotle,
the ability has been termed “phronesis” and can
be translated to “practical wisdom.” In order to
provide patients with proper clinical care, an
endodontist cannot rely on clinical research only
but needs also the practical skills of a craftsman,
where clinical and moral judgements are integral
components [7].
1 Introduction
1.6
he Still Large Proportion
T
of Root-Filled Teeth
with Less than Entirely
Satisfactory Treatment
Results
Despite the technological developments in our
discipline, so far, there is no convincing evidence
to suggest that the overall prognosis of root canal
treatments has increased over a period of
50 years. In epidemiological studies, the prevalence of apical periodontitis in root-filled teeth
repeatedly is reported to be 25–50% or even
more. The gap between “what is possible to
achieve” and “what is actually achieved” has to
be analyzed from cognitive, psychological, and
ethical perspectives [8].
1.7
The Implant Threat
The history of the dental implant era is not yet
completely written, but the long-term performance of replacements seems to be equal to
tooth-supported constructions. The technique is
nowadays spread worldwide. So far the overall
costs of replacing an endodontically involved
tooth with an implant are often higher than
those of a root canal therapy. But when more
and less expensive are brought to the market,
the implant technology may prevail over endodontics and, in particular, when primary root
canal treatment has failed [9].
1.8
he Internet as a Source
T
of Patients’ Information
Patients’ increased abilities to retrieve information resulted in a public that is more demanding
of better outcomes to treatment [10]. The
response from governments and authorities
could be more regulatory intervention to control perceived lapses in quality and ethics
among dentists. While the intent would be
noble, the implementation will probably lead to
an increase in administration time and less time
to devote to professional development and
patient care.
3
1.9
he Possible Link
T
Between General Health
and Root Canal Infections
The availability of information of varying quality
has likely contributed partly to regenerate the
interest in a possible association between endodontic infections and general health. Our discipline is facing an inevitable task to better describe
and evaluate any such connection [11].
1.10
The Awareness
of the Complexity of Biofilm
Infections
The increased understanding of the complexity and
diversity of the biofilms that are present in necrotic
root canals and many root-filled teeth has challenged the view that root canal treatment is about
getting root canals sterile. However, the essential
objective of endodontic treatment still remains, to
combat bacterial populations within the root canal,
at least to significantly reduce to levels that are compatible with periradicular tissue healing [12, 13].
1.11
he Two Sides
T
of the CBCT-Coin
With new technologies, like the advent of CBCT,
it also stands clear that postoperative situations
without symptoms and even teeth-­unobjectionable
conditions, as can be assessed on an intraoral
X-ray, may still prove to have signs of residual
inflammation and thus accommodate intraoral
microorganisms. These observations put your
finger on a crucial point. What should be regarded
as a period or sick and what needs to be treated
and what does not need to be addressed? [14, 15]
To retreat or not to retreat, that’s the question?
1.12
What Is a Disease?
It has been argued that both modern medicine and
dentistry face fundamental ethical problems if too
rigorous and consistent concepts of disease prevail.
T. Kvist
4
The discussion about different concepts of disease
goes back to ancient philosophy and has bewildered and engaged philosophers ever since. This
book about apical periodontitis in root-filled teeth
can only hint at the central questions. For further
reading, the interested reader should seek in books
on philosophy of medicine [16].
Two fundamentally different concepts of disease can by tradition be recognized.
The naturalist theory defines disease in terms of
biological processes. Disease is a value-free
concept, existing independently of its social
and cultural context. Disease is discovered,
studied, and described by means of science.
The normativist theory, on the other hand,
declares that there is no value-free concept of
disease. Rather than discovered, the concept
of disease is invented. It is contextual and
given by convention.
These theories address different aspects and pose
different challenges to medicine and dentistry. But
the two predominant concepts have been challenged
for several reasons. For example, they do not neither
one separately or together fully acknowledge all
important perspectives on human disorders. A different approach is to apply the “triad of disease, ill-
ness and sickness” [17]. The triad and its implications
on dentistry were elaborated by Hofmann and
Eriksen [18]. Kvist et al. [19] made initial attempts
to apply the theory to the problem of asymptomatic
root-filled teeth with apical periodontitis. In a
Chapter in Molar Endodontics edited by Peters
2017, I again and more profoundly discussed “the
triad” from a theoretical point of view [20].
The issue of “apical periodontitis in root-filled
teeth” is very well suited as an example of how
“the triad” can be applied to a human ailment and
give some new perspectives of this “dilemma”
that in different ways characterized and plagued
our discipline for so many years (Table 1.1).
Disease means the disorder in its’ physical form,
the biological nature, and the clinical and
paraclinical findings (histology, microbiology,
radiography, etc.).
Illness is used to describe a person’s own experience of the disease, how it feels, and what sufferings it gives now or in the future. Illness
also includes anxiety and anguish.
Sickness is the third label; it tries to capture the
social role of a person who has illness or disease (or both) in a particular cultural context.
What is eligible for being “sick” can consequently vary over time and between societies.
Table 1.1 An attempt to apply the triad of disease, illness, and sickness to root-filled teeth with apical periodontitis
Disease
Pathophysiological,
histological, microbiological,
and radiographic events
Validity
Objective
To study the medical facts of
Purpose from the
professions’ point of apical periodontitis in order to
improve knowledge of how to
view
prevent and cure
Phenomena studied
Illness
Pain, swelling, or other
symptoms present now
or in the future
Subjective
To identify and describe
the incidence, frequency,
and intensity for
patient-related outcomes
(pain, swelling, spread)
To value and accept or
not accept the situation
Sickness
Criteria for classification and
grading of disease
Intersubjective
To decide upon common criteria
for classification, define different
severities of disease, and
construct decision aids to guide
clinical action
To get an explanation of the
To understand what is regarded
Purpose from
situation
“sick,” respectively “healthy,” and
patients’ point of
to be helped to make a clinical
view
decision in his or her situation
The biofilm in root-filled teeth. Factors that can predict Reassessment of the criteria for
Example of issues
“success” and “failure” following
future pain or negative
of concern regarding The immunological response
impact on general health root canal treatment
“apical periodontitis to persistent root canal
in root-filled teeth” infection
The three approaches to disease do not replace but complement each other. It is also the case that they are strongly
intertwined. However, using the matrix of “disease,” “illness,” and “sickness” possibly makes it easier to understand and
to identify and rationalize the different natures of questions and discussions.
1 Introduction
1.13
The Authors
The endodontists contributing to this book about
apical periodontitis have that common denominator that they are or were in some way affiliated
with the Department of Endodontics or Oral
Microbiology at the University of Gothenburg.
This means that many of the ideas, experiences,
and knowledge conveyed in this book, for many
years and at a large number of hours, have been
worn and soaked in conjunction with lectures,
seminars, courses, and conferences.
In addition, we, who contributed as authors to
this book, have been cooperating and discussing
with many other endodontists, other specialists
(dentists and physicians), general practitioners,
philosophers, educators, and psychologists
throughout the years. No one mentioned and no
one forgotten.
However, a few people have in particular, but in
different ways over the years contributed to the
strong clinical and research environment that has
been “our school.” They have been our inspiration,
and their contribution has been particularly significant for creating, developing, and retaining endodontics as a strong discipline in Gothenburg,
Sweden, Scandinavia, and the world. Late
Professor Bure Engström, late Professor Åke
Möller, Professor Gunnar Bergenholtz, Professor
Gunnar Dahlen, and Professor Claes Reit all have
been invaluable, each in his own way.
We are all grateful and proud to have been
able to pursue parts of our professional education
and training in this inspiring setting.
DDS Pernilla Holmberg is a prosthodontists
and has a background in Malmö and Jönköping,
being two other dental colleges in Sweden with
strong research and clinical environments.
1.14
The Book
I hope that the various contributions to this book
will provide both a comprehensive and in-depth
description of the issues, which from different
aspects appear when dentists or doctors, their
patients, and other dental and health services are
faced with “apical periodontitis in root-filled teeth.”
5
As for the references, it has been our ambition
not to mention all the published works that have
dealt with an issue or topic. Our objective has
instead been carving out a number of key references. With these as a starting point, it is easy to, via
various search functions in publicly accessible databases such as PubMed, search further for more references. The general international trend with more
and more magazines and publications also means
that every reference list pretty soon tends to become
outdated. Those interested who want to keep themselves updated must constantly follow the development by taking advantage of new publications.
References
1. Ingle J. “Pull and be damned Road” Preface to first
edition in “Endodontics” 1965. In: Ingle J, Bakland L,
Baumgartner C, editors. Ingle’s endodontics6, 6th ed.
PMPH-USA; 2008.
2. Kassebaum NJ, Bernabé E, Dahiya M, Bhandari B,
Murray CJ, Marcenes W. Global burden of untreated
caries: a systematic review and metaregression. J Dent
Res. 2015;94:650–8.
3. Norderyd O, Koch G, Papias A, Köhler AA, Helkimo
AN, Brahm CO, Lindmark U, Lindfors N, Mattsson A,
Rolander B, Ullbro C, Gerdin EW, Frisk F. Oral health
of individuals aged 3–80 years in Jönköping, Sweden
during 40 years (1973–2013). II. Review of clinical and
radiographic findings. Swed Dent J. 2015;39:69–86.
4. Murray CG. Advanced restorative dentistry—a problem for the elderly? An ethical dilemma. Aust Dent
J. 2015;60(Suppl 1):106–13.
5. Callahan D. Health care costs and medical technology. In: Crowley M, editor. From birth to death and
bench to clinic: the Hastings Center bioethics briefing
book for journalists, policymakers, and campaigns.
Garrison, NY: The Hastings Center; 2008. p. 79–82.
6. Swedish Council on Health Technology Assessment.
Methods of diagnosis and treatment in endodontics—
a systematic review. Report no. 203; 2010. p. 1–491.
http://www.sbu.se
7. Bergenholtz G, Kvist T. Evidence-based endodontics.
Endod Top. 2014;31:3–18.
8. Dahlström L, Lindwall O, Rystedt H, Reit C. “It’s
good enough”: Swedish general dental practitioners
on reasons for accepting sub-standard root filling
quality. Int Endod J. 2017; https://doi.org/10.1111/
iej.12743. [Epub ahead of print].
9. Bateman G, Barclay CW, Saunders WP. Dental dilemmas: endodontics or dental implants? Dent Update.
2010;37:579–82. 585–6, 589–90 passim
10. Rossi-Fedele G, Musu D, Cotti E, Doğramacı
EJ. Root canal treatment versus single-tooth implant:
T. Kvist
6
11.
12.
13.
14.
15.
a systematic review of internet content. J Endod.
2016;42:846–53.
Khalighinejad N, Aminoshariae MR, Aminoshariae
A, Kulild JC, Mickel A, Fouad AF. Association
between systemic diseases and apical periodontitis.
J Endod. 2016;42:1427–34.
Wu MK, Dummer PM, Wesselink PR. Consequences
of and strategies to deal with residual post-treatment
root canal infection. Int Endod J. 2006;39:343–56.
Siqueira JF Jr, Rôças IN. Clinical implications and
microbiology of bacterial persistence after treatment
procedures. J Endod. 2008;34:1291–301.
Wu MK, Shemesh H, Wesselink PR. Limitations of
previously published systematic reviews evaluating the outcome of endodontic treatment. Int Endod
J. 2009;42(8):656–66.
Haridas H, Mohan A, Papisetti S, Ealla KK. Computed
tomography: will the slices reveal the truth. J Int Soc
Prev Community Dent. 2016;6(Suppl 2):S85–92.
16. Wulff HR, Pedersen SA, Rosenberg R. Philosophy of
medicine: an introduction. 2nd ed. Oxford: Blackwell
Scientific; 1990.
17. Hofmann B. On the triad disease, illness and sickness.
J Med Philos. 2002;27:651–73.
18. Hofmann BM, Eriksen HM. The concept of disease: ethical challenges and relevance to dentistry and dental education. Eur J Dent Educ. 2001;5:2–8. discussion 9–11.
19. Kvist T, Heden G, Reit C. Endodontic retreatment
strategies used by general dental practitioners. Oral
Surg Oral Med Oral Pathol Oral Radiol Endod.
2004;97:502–7.
20. Kvist T. The outcome of endodontic treatment. In:
Peters OA, editor. The guidebook to molar endodontics. Heidelberg: Springer-Verlag Berlin Heidelberg;
2017.
2
Incidence, Frequency,
and Prevalence
Fredrik Frisk
As our world continues to generate unimaginable amounts of data, more data lead to
more correlations, and more correlations can lead to more discoveries.
Hans Rosling (1948–2017) was a Professor of International Health,
Department of Public Health Sciences/Global Health (IHCAR),
Karolinska Institute, and founder of the Gapminder Foundation.
Abstract
Epidemiological studies may provide important information on frequency
and prevalence of apical periodontitis and root-filled teeth. They may also
present data on outcome of endodontic treatment in community dental
care along with determining factors. Results from epidemiological studies
can be used to generate hypotheses to be tried in clinical studies in which
causal relationships may be established.
The prevalence of apical periodontitis in root-filled teeth is high and
statistically determined by root filling quality and, to a lesser extent, restoration quality. The long-term retention of root-filled teeth may be dependent on the restoration.
Data on incidence of apical periodontitis in root-filled teeth or exacerbation of apical periodontitis in root-filled teeth are scarce or lacking due
to methodological difficulties.
2.1
Introduction
Wherever studied apical periodontitis is a frequent finding in root-filled teeth. Epidemiological
data and research may not be seen as an important adjunct by the clinician. Epidemiology is
concerned with groups of individuals while
the clinician focuses on the individual patient.
F. Frisk, DDS, PhD
Department of Endodontology, Institute for
Postgraduate Dental Education, Jönköping, Sweden
Department of Endodontology, Institute of
Odontology, The Sahlgrenska Academy, University
of Gothenburg, Göteborg, Sweden
e-mail: fredrik.frisk@rjl.se
© Springer International Publishing AG 2018
T. Kvist (ed.), Apical Periodontitis in Root-Filled Teeth,
https://doi.org/10.1007/978-3-319-57250-5_2
What relevance may epidemiological data have
for the clinician and for the patient? It may help
to answer some questions about, for example,
endodontic treatment; which prognosis is
expected and what are the determining factors? Is
the condition prevalent and which symptoms
may be expected? What are the risks involved if
treated or left untreated? Health planners and
policy makers may use data to allocate resources
in order to use them effectively. They need
answers to some questions as well; is the condition becoming more or less prevalent? Is the condition becoming more difficult to treat? Is there a
need for educational efforts in order to make
treatment more effective?
7
F. Frisk
8
Data from population surveys inform us that
there is a positive correlation between poor root
filling quality and apical periodontitis. Although
educational efforts and technical improvement
have resulted in better root filling quality, no
decrease in apical periodontitis in root filled teeth
is seen. One explanation may be that more molar
teeth are endodontically treated, and most patients
retain their own teeth when they get older, making
endodontic treatment even more challenging.
Even though crucial information is lacking in
comparison to controlled clinical studies, population surveys are critical to investigate periapical
status and outcome of endodontic treatment in
the general population in community dental care.
Therefore, it is important that they are spread to
include as many populations as possible and
repeated to take time trends into account and render updates on disease prevalence.
2.2
opulation Surveys vs.
P
Clinical Studies
Most clinicians find endodontic treatment to be a
complicated and delicate procedure. Thus, technical difficulties may account for a high prevalence of apical periodontitis in root-filled teeth.
Population surveys confirm that clinicians
repeatedly fail to meet high demands on the
technical quality of the root filling as interpreted
on a radiograph. When investigated in population surveys, the radiograph is usually the only
source of information. Nevertheless, data from
population surveys frequently confirms the
established view on root filling quality and its
impact on the periapical status. However, in
comparison to the clinical study, crucial information about the endodontic treatment performed is lacking. Clinicians contributing with
data to clinical studies most often work in education and specialist centers with excellent facilities for endodontic treatment. Moreover, they are
aware of their participation in the study which
may contribute to a higher level of motivation,
further affecting treatment quality. Consequently,
data from clinical studies may contribute to an
unrealistic expectation on the outcome of root
canal treatment. A common misconception when
comparing results from clinical studies and population surveys is that general practitioners frequently are unsuccessful in clinical endodontics,
while endodontists are highly successful.
Available data do not support such a notion.
However, interpreted correctly, data from population surveys may be representative for the
result of endodontic treatment in community
routine dental care (effectiveness). Data from
clinical studies may represent what can be
achieved with endodontic treatment (efficacy).
Data from contemporary population surveys
are presented as means from a population and do
not support conclusions as to which interventions
that provide effective treatment results. For
example, rotary instrumentation is widely considered as a valuable adjunct in endodontic treatment and has been used, and widely spread, in
clinical practice for well over a decade. The benefit on a population level in terms of outcome
(prevention and healing of apical periodontitis,
tooth retention) and cost-effectiveness has yet to
be shown.
2.3
Epidemiological Study
Design
In endodontic epidemiology, mainly cross-­sectional
and longitudinal studies are used. Below, the reader
will find a brief presentation of these study designs
as well as an introduction of some terms which
may need clarification. Prevalence and frequency
are synonymous terms. In this text prevalence will
mean the percentage of individuals (with apical
periodontitis) and frequency will mean percentage
of teeth (with apical periodontitis) at a certain point
in time. Incidence will mean percentage of teeth
(getting apical periodontitis) during a determined
period of time.
2.3.1
Cross-Sectional Studies
The most common study in endodontic epidemiology is the cross-sectional study. A synonymous term is prevalence study. It measures the
2
Incidence, Frequency, and Prevalence
prevalence (individual level) or frequency (tooth
level) of a certain entity at a given point in time.
The entity to be measured is required to be
chronic or long-lasting such as apical periodontitis or root-­filled teeth. Acute events, short-lasting conditions, or exacerbations are not eligible
for the cross-sectional study since the time for
examination may not coincide with the event or
condition to be studied. In the context of apical
periodontitis in root-filled teeth, a major drawback is the lack of knowledge about the endodontic treatments in the teeth studied. If a
certain tooth has a periapical destruction, it
should be crucial to know when the treatment
was performed and which periapical status the
tooth had at the outset of treatment. Is the periapical destruction developing or healing? If a
tooth appears to have a healthy periapex, apical
periodontitis may be developing even though it
is not radiographically detectable. A longitudinal
study on this issue reported that the number of
developing and healing periapical destructions
were almost the same and thus minimizing the
problem [1] whereas another study did not support this conclusion [2]. Another drawback is
that causality cannot be studied in a cross-sectional study since the relation between two variables is studied at one point in time only.
However, cross-sectional studies are frequently
used to investigate associations between different variables such as root filling quality and periapical status. Frequently, poor root filling quality
is found to be associated with periapical destructions, but in a cross-sectional study it cannot be
established as a cause, or risk factor, for apical
periodontitis. It may serve as an indicator of
poor treatment quality and/or ineffective endodontic treatment. Thus, poor root filling quality
may be the aggregate result of poor access preparation, poor aseptic technique, poor instrumentation, and poor irrigation.
Cross-sectional studies on root-filled teeth
and apical periodontitis are spread geographically uneven. A large fraction of the total number of studies has been conducted in
Scandinavia. However, during recent years several studies from mainly European countries,
but also from other continents, have emerged.
9
This is of great importance since data from one
setting cannot be interpreted as representative
for another setting.
As can be seen in Table 2.1, the prevalence
and frequency of apical periodontitis differ
between different studies. Of course, this can be
due to varying prevalence of disease in different populations and an indicator of poor treatment quality or poor accessibility to dental care.
It may also reflect the use of different definitions for a healthy and diseased periapical area,
respectively. Also, extraction frequency needs to
be taken into account. Thus, a low prevalence of
apical periodontitis in root-filled teeth may not
necessarily represent high treatment quality. It
may merely be a result of extraction of teeth with
persistent apical periodontitis. Also, selection of
teeth with prerequisites for a favorable outcome
(no preoperative apical periodontitis, no technical complications, or technically demanding
­treatment) may influence the results.
2.3.2
Longitudinal Studies
These studies follow a number of subjects over a
period of time. A synonymous term is cohort
study. In the context of population surveys, no
intervention is done—all subjects go about their
ordinary life and treatments as usual. The condition to be studied needs to be frequent enough in
order to provide a sufficient number of cases to
be compared with non-cases. A “case” is an individual, or a tooth, with the condition under study,
for example apical periodontitis. Also, the length
of time between baseline and follow-up needs to
be adjusted in relation to what is intended to be
investigated. It needs to be long enough for the
event under study to take place and short enough
to be registered before the event is impossible to
identify. Apical periodontitis is prevalent enough
to produce a sufficient number of cases. However,
a healthy tooth may develop apical periodontitis
and be root canal treated and even extracted
between baseline and follow-up if the time span
is too long. Under such circumstances a lot of
information is lost and should warrant shorter
follow-up periods.
Study
Bergenholtz et al. [34]
Boltacz-Rzepkowska [35]
Boucher et al. [36]
Buckley and Spångberg [37]
Chen et al. [38]
Da Silva et al. [39]
De Cleen et al. [40]
De Moor et al. [41]
Dugas et al. [42]
Dutta et al. [6]
Eckerbom et al. [43]
Eriksen and Bjertness [45]
Eriksen et al. [46]
Estrela et al. [47]
Georgopoulou et al. [48]
Gulsahi et al. [49]
Hollanda et al. [50]
Hommez et al. [51]
Huumonen et al. [52]
Ilić et al. [53]
Jersa and Kundzina [54]
Jimenez-Pinzon et al. [55]
Kabak and Abbott [56]
Kalender et al. [57]
Kamberi et al. [58]
Kirkevang et al. [59]
Kim [60]
Loftus et al. [61]
Lupi-Pegurier et al. [62]
Marques et al. [63]
Country
Sweden
Poland
France
USA
USA
Australia
Netherlands
Belgium
Canada
Scotland
Sweden
Norway
Norway
Brazil
Greece
Turkey
Brazil
Belgium
Finland
Serbia
Latvia
Spain
Belarus
Cyprus
Kosovo
Denmark
South Korea
Ireland
France
Portugal
Radiograph
Apical/FMR
Apical/FMR
Apical/FMR
Apical/FMR
Panoramic
Panoramic
Panoramic
Panoramic
Apical/FMR
CBCT
Apical/FMR
Apical/FMR
Apical/FMR
Apical/FMR
Apical/FMR
Panoramic
Panoramic
Apical/FMR
Panoramic
Panoramic
Panoramic
Apical/FMR
Panoramic
Panoramic
Panoramic
Apical/FMR
Panoramic
Panoramic
Panoramic
Panoramic
Sample
Patient
Patient
Patient
Patient
Population
Patient
Patient
Patient
Patient
Patient
Patient
Population
Population
Patient
Patient
Patient
Patient
Patient
Population
Patient
Patient
Patient
Patient
Patient
Patient
Population
Patient
Patient
Patient
Population
Prevalence
RF (%)
57
25
62
4.1
38.8
21.4
44.6
63.1
34.3
39.2
83.5
56
24
38
65.6
23.8
21.4
32.5
61
85
87
40.6
80
64
12.3
52
22.8
31.8
7.3
22
52.2
39.2
40.4
45.4
47.4
5.2
36.5
0.6
13.6
18.2
51.8
7
4.2
45
7
3.4
6.0
6.6
3.1
5.8
63
3.5
14
85.5
1.4
93.8
72
61.1
12
68
46.3
42.3
33.1
31.5
26
62
5.1
25.0
21.7
2.0
2
31
64.5
60
38.1
26.4
35.5
29.7
7.4
31.3
45.6
Frequency
AP RF (%)
Frequency
AP total (%)
30.5
Prevalence
AP (%)
6.1
Table 2.1 Cross-sectional studies reporting on prevalence of root-filled teeth (RF) and apical periodontitis (AP), frequency of apical periodontitis and frequency of apical periodontitis in root-filled teeth.”
10
F. Frisk
Matijevic et al. [64]
Moreno et al. [65]
Paes da Silva et al. [5]
Peciuliene et al. [66]
Persic et al. [67]
Peters et al. [68]
Petersson et al. [69]
Saunders et al. [71]
Sunay et al. [72]
Skudutyte-Rysstad et al. [73]
Sidaravicius et al. [74]
Tavares et al. [12]
Touré et al. [75]
Tercas et al. [76]
Tolias et al. [77]
Tsuneishi et al. [78]
Weiger et al. [79]
Ödesjö et al. [80]
Özbaş et al. [81]
Croatia
Colombia
Brazil
Lithuania
Croatia/Austria
Netherlands
Sweden
Scotland
Turkey
Norway
Lithuania
France
Senegal
Brazil
Greece
Japan
Germany
Sweden
Turkey
Panoramic
Apical/FMR
CBCT
Apical/FMR
Panoramic
Panoramic
Apical/FMR
Apical/FMR
Panoramic
Apical/FMR
Apical/FMR
Apical/FMR
Apical/FMR
Apical/FMR
Panoramic
Apical/FMR
Panoramic/Apical
Apical/FMR
Apical/FMR
Patient
Patient
Patient
Patient
Patient
Patient
Patient
Patient
Patient
Population
Population
Patient
Patient
Patient
Population
Patient
Patient
Population
Patient
75.9
49
51.4
43.1
47.3/62.1
2.5
93
54
47
23
72
33
35.5
67.5
62.3
86.5
3.0
43.2
1.6
8.7
4.9
53.5
1.1
7.2
4.6
42.5
40
24.1
77
67.7
4.2
16
70
59.6
5.9
69.8
61
2.9
38
24.5
35.4
3.4
8.5
56.1 (roots)
43
35
26.5
58.1
2
Incidence, Frequency, and Prevalence
11
12
Longitudinal studies measuring the incidence of apical periodontitis are scarce. They are
expensive to conduct and difficult to manage. A
major problem is loss to follow-up. If too many
participants are prevented from participating,
or choose not to, it should be questioned as to
whether the remaining sample is representative
for the population.
F. Frisk
may be examined with regard to pulpal sensitivity to confirm the diagnosis. In an epidemiological study exclusively based on radiographs, this
information is lacking but it is usually considered
uncontroversial since the most probable diagnosis is apical periodontitis [3]. Older studies investigating root-filled teeth and apical periodontitis,
more often than today, used apical radiographs.
During recent decades panoramic radiographs
have emerged as a simpler and more economical
2.3.3 Methodology
technique. Also, and more important, it exposes
the individual with a lower radiation dose com2.3.3.1 Selection
pared to a full mouth examination using apical
When reviewing studies in the field of endodon- radiographs. In the context of epidemiological
tic epidemiology, it is apparent that the most studies, the panoramic radiograph has been demcommon individual studied is the one who seek onstrated as reasonably effective as the apical
dental care at a dental school and have been radiograph when apical periodontitis is studied
examined with full-mouth radiographs and/or [4]. It performs worse than the apical radiograph
panoramic x-rays. This is a convenient approach when root filling quality is studied. Cone beam
since researchers do not have to make an effort to CT (CBCT) is a rather new technique which has
invite individuals to the examination. Also, if shown to be promising as an adjunct in endodonindividuals examined are exposed to radiation in tic diagnostics. However, it has not been used in
the context of seeking dental care, there will be a endodontic epidemiology other than in a few studlesser ethical dilemma as to whether the radio- ies [5, 6]. It may be viewed as doubtful if it is juslogical examination was justified or not. However, tifiable to expose healthy individuals with a much
it is reasonable to assume that individuals seek- larger radiation dose (compared to a full mouth
ing dental care are not representative for the examination) when studying the prevalence and
whole population. This assumption may be espe- frequency of apical periodontitis. Apical pericially true for patients seeking dental care at a odontitis is a prevalent condition and not life-­
dental school. These patients may have more threatening other than for selected patients. It
extensive treatment needs and may have smaller may thus be argued that CBCT is not suited for
financial resources than the population as a screening. Others claim that it is justifiable and
whole. Thus, in order to render samples represen- advocate the use of CBCT in epidemiological
tative for the population, researchers should con- studies, highlighting the drawbacks with two-­
sider other approaches such as studying a dimensional techniques [5].
randomized sample of individuals. If large
It is acknowledged that when studying apical
enough, the randomized sample may be regarded periodontitis or root filling quality, researchers
as representative for the population from which it have to consider a variation both between observwas sampled. Studies using randomized samples ers and also within observers over time [7]. This
are in minority in endodontic epidemiology. is often referred to as inter- and intraobserver
Despite the methodological considerations dis- variation, respectively. In order to cope with the
cussed, the number of studies using convenience problem, two different strategies have been
sampling is still in majority.
developed to reduce observer variation when
studying apical periodontitis.
2.3.3.2 Radiographic Examination
Reit and Gröndahl [8] suggested that observer
Does the periapical destruction always represent variation may be reduced if the number of
apical periodontitis? In a clinical context non-­ false-­
positive findings is kept to a minimum
root-­
filled teeth with a periapical destruction by instructing the observers to only register a
2
Incidence, Frequency, and Prevalence
13
Fig. 2.1 PAI-Reference scale with scores 1–5 and corresponding radiological and histological periapical expressions [10]
p­ eriapical destruction when certain, introducing
a five-scale index where score 1 = “periapical
destruction of bone definitely not present” and
5 = “periapical destruction of bone definitely
present.” This index is also called the PRI-index
(probability index). Reit [9] found that calibration of observers had only limited benefits in
reducing observer variation.
Örstavik et al. [10] presented the periapical
index (PAI). In contrast to Reit [9] it is proposed
that observers should be calibrated, and in contrast to Reit and Gröndahl [8] there is no overall
strategy to reduce false-positive findings. PAI
works as follows: observers are presented with a
five-graded scale with radiographs with different periapical expressions ranging from periapical health (score 1) to an aggravating periapical
condition (score 2–5) (Fig. 2.1). The periapical
expressions on the radiographs have been validated with the histological periapical expression
in a previous study using biopsies from an
autopsy material [3]. For the purpose of calibration of observers to PAI, observers are instructed
to use the scale when observing 100 radiographs. When in doubt, observers are instructed
to assign a higher score. The reason for this is
findings from Brynolf [3] where the histological
periapical expression always was more severe
than the radiological periapical expression. The
registrations are then compared to a “golden
standard” constructed by a panel of observers
who have assigned “true” scores to all 100
teeth. If the observer variation is low enough
Table 2.2 Text reference for the periapical expression
according to modified Strindberg criteria as adopted by
Reit and Hollender [7]
0 = Normal periapical condition
1 = Increased width of the periodontal membrane
space. Lamina dura continuous
2 = Increased width of the periodontal membrane
space. Lamina dura diffuse
3 = Periapical radiolucency
compared to the “golden standard,” observers
may use PAI in their study.
An alternative to PAI, when defining a healthy
and diseased periapex, modified Strindberg criteria may be used [7, 11]. There is only a text reference to describe the periapical expression
(Table 2.2).
Studies evaluating the different approaches
are scarce. However, Tavares et al. [12] used both
PAI and modified Strindberg criteria. There is no
information as to which strategy that was adopted
when the modified Strindberg criteria were used.
Authors reported approximately the same prevalence of apical periodontitis within the same
sample regardless of method used. Tarcin et al.
[13] reported on results from comparing PAI,
PRI, and modified Strindberg criteria. PAI had
higher interobserver agreement, reflecting the
use of reference radiographs. When dichotomizing PAI and PRI, both inter- and intraobserver
agreement were higher than for the original
5-scale PAI- and PRI-indices, respectively, and
for the modified Strindberg criteria.
F. Frisk
14
2.4
esults from Population
R
Surveys: What We Know
and What We Don’t
2.4.1
requency and Prevalence
F
of Apical Periodontitis
and Root-Filled Teeth
A growing number of cross-sectional studies
provide us with data on apical periodontitis in
root-­filled teeth. However, longitudinal data are
scarce, and thus knowledge on the natural course
of the root-filled tooth with untoward events and
healing pattern is incomplete.
Cross-sectional studies display a wide range
in the frequency of root-filled teeth and apical
periodontitis, both on the tooth level (frequency)
as well as the individual level (prevalence). As
previously discussed this may reflect differences
between populations but also differences in
study design and definitions of outcome measures. Within the studies data often reveals an
increasing frequency of root-filled teeth and apical p­ eriodontitis with increasing age. They also
report on a decreasing number of teeth. The latter may explain the increasing frequency alone
but also the number of root-filled teeth increases
with age [14].
Repeated cross-sectional studies show a trend
toward decreasing frequency of apical periodontitis and root-filled teeth for comparable age
groups. This is probably a result of a concomitant
decrease in caries frequency and is thus expected
and uncontroversial. A more unexpected finding
is that the frequency of apical periodontitis in
root-filled teeth is unchanged over time. Changes
in treatment protocols, new techniques and materials, and an increasing knowledge in microbiology and immunology should be expected to
improve the results of endodontic treatment.
What may be possible reasons for this inconsistency? Clinicians today probably treat more
advanced and challenging cases than in earlier
decades. Frisk et al. [14] showed that molars
were more often treated than premolars and incisors in 2003. In 1973 it was the other way around.
Undeniably technically advanced systems for
rotary or reciprocating instrumentation improve
the treatment quality with regard to instrumentation and root filling quality. This is often highlighted in endodontic literature and marketing of
endodontic armamentarium. However, asepsis
and biological necessities (a complex bacterial
flora protected in a biofilm, need for copious irrigation with sodium hypochlorite) may need
boosted attention.
In longitudinal studies only small variations in
the frequency of apical periodontitis with increasing age is seen. Results from different studies are
inconclusive [1, 15–17]. The frequency of root-­
filled teeth increases. This result is consistent
between studies. Kirkevang et al. [15] also demonstrated that the increase was less marked in
younger age groups and that they received their
root fillings later in life indicating an improvement in oral health. Studies reporting on changes
in the frequency of root-filled teeth with apical
periodontitis with increasing age show conflicting results.
2.4.2
isk Indicators for Apical
R
Periodontitis in Root-Filled
Teeth
2.4.2.1 Tooth-Specific Risk Indicators
Is it possible to identify a set of criteria indicating
higher risk for persisting or developing apical
periodontitis in root-filled teeth?
In epidemiological studies, the most common
predictor for apical periodontitis in root-filled
teeth is poor root filling quality. This association
is demonstrated in almost all studies pertaining to
apical periodontitis and root-filled teeth. It should
be acknowledged that poor root filling quality is
not a cause of apical periodontitis. It merely
serves as an indicator or predictor for ineffective
treatment or prevention of the root canal infection. As previously mentioned repeated cross-­
sectional studies report that the root filling quality
has improved over time without a concomitant
decrease in the frequency of apical periodontitis
in root-filled teeth. Thus, other reasons for persistent apical periodontitis and ineffective treatment
2
Incidence, Frequency, and Prevalence
15
or prevention of the root canal infection must be
considered. The quality of restoration has gained
some attention as a risk indicator and has been
studied by several authors. While data are inconclusive as to whether poor restoration quality is
an independent risk indicator for apical periodontitis in root-filled teeth, the combination of adequate restoration and adequate root filling
increases the chance for periapical healing [18].
Less studied is the impact of type of restoration
on periapical status in root-filled teeth. A recent
study reported that large composite fillings and
large mixed fillings (amalgam and composite)
were predictive of apical periodontitis when controlling for root filling quality [19].
Results are inconclusive as to whether type and
quality of restorations in root-filled teeth predicts
a higher risk for apical periodontitis. Root filling
quality remains as the most significant predictor
for apical periodontitis in population surveys.
2.4.2.2 Individual-Specific Risk
Indicators
Is it possible to identify individuals with a specific set of risk factors or risk indicators for apical
periodontitis in root-filled teeth?
Conditions and behavioral factors have been
studied as risk indicators for apical periodontitis
in root-filled teeth in a few studies. Smoking has
repeatedly been reported as a predictor for apical
periodontitis. In a systematic review five out of
six cross-sectional studies reported a statistically
significant association between smoking and
periapical bone lesions [20]. There is no established biological mechanism between smoking
and apical periodontitis, and present studies do
not disclose any causal relationship between
smoking and apical periodontitis. The reported
association between smoking and apical periodontitis in root-filled teeth may, to some extent,
be explained by factors related to study design
and quality: small samples, misclassification of
nonsmokers, and poor control of possible confounders. Additionally, diabetes has been reported
to be associated with apical periodontitis on both
individual level and tooth level [21]. Also, dental
care habits may be associated with apical periodontitis, whereas socioeconomic status has not
been confirmed as a predictor [22, 23].
Patients with irregular dental habits and smokers may be suspected to be at higher risk for having root-filled teeth with apical periodontitis.
There is no evidence to claim that endodontic
treatment of a specific tooth among these patients
should have a worse prognosis compared to other
groups of patients. It may be speculated that the
higher prevalence of apical periodontitis may be
explained by behavioral factors such as dental
care habits and a different attitude to health and
dental care.
2.4.3
I ncidence of Apical
Periodontitis in Root-Filled
Teeth
Is it possible to predict which root-filled teeth
that are at higher risk for developing apical
periodontitis?
In Table 2.3 incidence data for apical periodontitis in root-filled teeth are listed. Those
teeth were root-filled and without radiological
evidence of apical periodontitis at base line.
Data on when the teeth were endodontically
Table 2.3 Data from longitudinal (follow-up) studies
Kirkevang et al. [15]
Petersson et al. [24]
Eckerbom et al. [44]
Petersson et al. [70]
Follow-up
(years)
11
11
20
20
Incidence of root
canal treatmenta
1.7% (140/8258)
3.3% (70/2100)
5.5% (155/2825)
Retreatments excluded
b
Root-filled teeth and pulpotomized teeth included
a
Incidence of AP
in root-filled teeth
32% (67/208)
12.4% (17/137)
8% (23/273)
Loss of
root-filled teeth
13.9% (56/402)
12.4% (32/258)b
28.8% (113/393)
35% (159/449)
F. Frisk
16
treated and on which indication is not available.
According to Petersson et al. [24] the root filling
quality was a significant predictor for development of apical periodontitis. Kirkevang et al.
[25] did not find poor root filling quality to be
predictive for development of apical periodontitis, but instead increased the risk for persistent
apical periodontitis.
As can be seen, data from population surveys
do not identify factors that consistently predict which root-filled teeth will develop apical
periodontitis.
2.4.4
Loss of Root-Filled Teeth
Longitudinal studies conclusively show that
root-­filled teeth are at higher risk to be lost
than non-­root-­filled teeth [26]. Studies investigating the reasons for loss of root-filled teeth
have reported that other reasons than apical
periodontitis are more frequent. Caries, failed
restorations, amount of tooth substance, and
marginal periodontitis have been reported as
risk factors for loss of root-­filled teeth [27–29].
On an individual level, one study reported that
high age, number of lost teeth, and amount of
plaque were predictive of loss of root-filled
teeth [30]. Interestingly, endodontic factors
represent a small fraction of reasons for extraction of root-filled or endodontically treated
teeth. Several studies have reported on the benefit of crown restoration on root-filled teeth.
Aquilino and Caplan [31] showed that crown
placement on molars increased survival significantly compared to root-filled molars without full crown coverage. Landys-Borén et al.
[32] reported similar results but not limited to
molars. Fransson et al. [33] also reported on
a higher survival rate for teeth with indirect
restorations compared to direct restorations.
However, the difference was small, 93.1 and
89.6%, respectively.
Root-filled teeth with substantial loss of tooth
substance and root-filled molars without full
crown coverage seem to be at higher risk of being
lost. Individuals with poor dental habits seem to
be at higher risk for loss of root-filled teeth.
Take Home Lessons
• Use data from epidemiological studies
to improve endodontic treatment and
care of patients with endodontic conditions. Do not use it to compare data on
outcome from clinical studies conducted
in education or specialist clinics.
• Use data from epidemiological studies
to compare with your own and your colleagues’ clinical experience. Is your
experience at variance with epidemiological data?
• There is a great potential for improvement of the outcome of endodontic
treatment. Besides adequate root canal
treatment, careful case selection and
treatment planning including choice of
adequate restoration may improve the
outcome.
Benchmark Papers
• Frisk F, Hugoson A, Hakeberg
M. Technical quality of root fillings and
periapical status in root filled teeth in
Jönköping, Sweden. Int Endod J.
2008;41:958–68. This repeated cross
sectional study reported on the frequency of apical periodontitis in root
filled teeth on three occasions over a
20-year period. The results also highlighted that an improved root filling
quality has not resulted in a lower frequency of apical periodontitis in root
filled teeth.
• Kirkevang LL, Vaeth M, Wenzel A. Ten-­
year follow-up of root filled teeth: a
radiographic study of a Danish population. Int Endod J. 2014;47:980–8. One
of few longitudinal studies that reports
on incidence of apical periodontitis in
root filled teeth and related factors.
• Gillen BM, Looney SW, Gu LS,
Loushine BA, Weller RN, Loushine RJ,
Pashley DH, Tay FR. Impact of the
2
Incidence, Frequency, and Prevalence
quality of coronal restoration versus the
quality of root canal fillings on success
of root canal treatment: a systematic
review and meta-analysis. J Endod.
2011;37:895–902. Recommended reading for anyone pondering the association between the quality of the
restoration and apical periodontitis in
root filled teeth. The paper provides a
systematic review of the literature as
well as a meta-analysis. The authors
conclude that the combination of adequate root filling and adequate restoration increase the chance for a healthy
periapical condition.
• Örstavik D, Kerekes K, Eriksen
HM. The periapical index: a scoring
system for radiographic assessment of
apical periodontitis. Endod Dent
Traumatol. 1986;2:20–34. An important
paper introducing the PAI-index which
over time have found an increasing
number of users in epidemiological and
clinical studies. Recommended reading
for those who are planning a study
including evaluation of periapical status in radiographs and wants to understand how observation variation may be
handled.
References
1. Petersson K. Endodontic status of mandibular premolars and molars in an adult Swedish population. A longitudinal study 1974–1985. Endod Dent Traumatol.
1993;9(1):13–8.
2. Kirkevang LL, Vaeth M, Hörsted-Bindslev P,
Wenzel A. Longitudinal study of periapical and
endodontic status in a Danish population. Int Endod
J. 2006;3:100–7.
3. Brynolf I. A histological and roentgenological study
of the periapical region of human upper incisors.
Odontol Revy. 1967;18(Suppl 11):1–176.
4. Ahlqwist M, Halling A, Hollender L. Rotational panoramic radiography in epidemiological studies of
dental health. Comparison between panoramic radiographs and intraoral full mouth surveys. Swed Dent
J. 1986;10(1–2):73–84.
17
5. Paes da Silva Ramos Fernandes LM, Ordinola-­
Zapata R, Húngaro Duarte MA, Alvares Capelozza
AL. Prevalence of apical periodontitis detected in
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3
Aetiology of Persistent Endodontic
Infections in Root-Filled Teeth
Luis E. Chávez de Paz
The 4th sort of creatures … which moved through the 3 former sorts, were incredibly
small, and so small in my eye that I judged, that if 100 of them lay one by another, they
would not equal the length of a grain of course sand; and according to this estimate, ten
hundred thousand of them could not equal the dimensions of a grain of such course sand.
There was discovered by me a fifth sort, which had near the thickness of the former, but
they were almost twice as long.
Antonie van Leeuwenhoek 1676—in a letter to about what he saw when looking to
plaque from his own teeth through one of the first microscopes.
Abstract
Post-treatment endodontic infections are caused by microorganisms forming biofilm structures that remain deep-seated in root canals or extra-­
radicular surfaces. Bacteria in biofilms are difficult to eliminate as they are
protected from both the host immune response and antimicrobials. As
revealed by culture microbiological analysis and high-throughput DNA
sequencing, the microbiota in post-treatment endodontic infections is
composed by oral pathogens mixed with species that are considered
‘harmless’ or ‘transient’ commensals. However, our knowledge concerning the mechanisms that lead to the survival of these mixed microbial
communities in root-filled teeth as well as the mechanisms by which they
participate in post-treatment infections have only recently begun to
advance. This chapter explores clinical and basic biological aspects to gain
deeper understanding of microbial etiological factors that play a role in
persisting infections of endodontically treated teeth.
3.1 Introduction
Endodontic treatment aims to remove bacteria
from infected root canals by mechanical instrumentation in combination with chemical antimicrobial agents. These treatment procedures apply
physical forces to remove bacteria by direct contact of hand- or machine-driven instruments on
L.E. Chávez de Paz, DDS, MS, PhD
Division of Endodontics, Department of Dental
Medicine, Karolinska Institute, Huddinge, Sweden
e-mail: luis.chavez.de.paz@ki.se
© Springer International Publishing AG 2018
T. Kvist (ed.), Apical Periodontitis in Root-Filled Teeth,
https://doi.org/10.1007/978-3-319-57250-5_3
the surfaces of the root canals. The use of antimicrobials in the form of irrigants complements the
physical action to remove root canal bacteria.
However, in spite of these mechanical/chemical
efforts and the host’s innate and adaptive defence
mechanisms, post-treatment endodontic infections occur with relative high frequency (see
Chap. 2). These persistent infections are usually
clinically silent and are characterized by chronic
inflammatory reactions taking place in the tissues
surrounding the apexes of roots.
The underlying pathogenesis of persistent
endodontic infections is associated with the
21
L.E. Chávez de Paz
22
Environmental
disturbances
Original root canal
microbiota
Simplification
Resilience
Fig. 3.1 Ecological moments that determine the selection
of a post-treatment root canal community. Environmental
disturbances such as mechanical instrumentation, irrigation with antimicrobials and inter-appointment medication
cause a simplification of the original root canal microbiota.
Further disturbances such as lack of nutrients and interactions with the host’s immune cells lead to the formation of
a resilient microbiota.
presence of microbial biofilm communities that
interact with host cells triggering an inflammatory and immune response [1–3]. Persisting
microbial biofilm communities formed on dentinal walls or on extra-radicular cementum are
difficult to eliminate in part due to their high tolerance/resistance to host defences and antimicrobials. Clinical studies have established that these
microbial communities are mainly composed by
Gram-­positive facultative anaerobic bacteria [4–
7]. Streptococcus, Lactobacillus and Actinomyces
are examples of species that are considered normal inhabitants of the oral cavity and that have
been also isolated from root-filled teeth with apical periodontitis. Other nonoral species such as
Enterococcus faecalis have also been found with
relatively high frequency [4–8]. Overall, the
microbiota remaining after endodontic procedures is proposed to be a subpopulation of the
original root canal microbiota. Therefore, the
mechanisms by which this resistant subpopulation is selected are of interest as it may reveal
important pathogenic traits included in the adaptation and survival of these microorganisms.
ota [9]. The first process occurs directly after or
during root canal treatment, where the application of antibacterial solutions, dressings, etc.,
triggers a simplification of the original root canal
microbiota [9]. These environmental changes
select for a subset of the microbiota with a high
resistance and tolerance (see below). The second
process comprises the resilience of the remaining community, where physiological adaptive
factors play a crucial role to establish as a resilient microbial community [9]. Figure 3.1 illustrates these ecological processes as they are
central to understand how bacteria may survive
after treatment. This chapter will describe the
main components of this ecological hypothesis
as they have a direct implication in the aetiology
of post-­treatment infections: formation of biofilms, localization of microbial communities
beyond the reach of chemomechanical treatment, interactions with the host and resistance
and tolerance of bacteria.
­
3.1.1
Ecological Scenario
There are two main ecological processes to take
into consideration that might affect the composition and function of the post-treatment microbi-
3.2
Root Canal Biofilms
The biofilm concept recognizes biofilm formation as a key mechanism linked to microbial
survival, and its application in endodontics has
led to the understanding of their involvement
in the pathogenesis of endodontic infections
[1–3]. In general, biofilm formation reflects an
3
Aetiology of Persistent Endodontic Infections in Root-Filled Teeth
e­ ssential mechanism of microbial adaptation to
environmental conditions. Bacteria in biofilms
are surrounded by a matrix of bacterial exopolysaccharides and exogenous substances (polysaccharides, proteins, mineral crystals, extracellular
DNA) [10, 11] that protect them from the host’s
immune defences. Antibodies and phagocytes
have difficulties to penetrate into the biofilm and
may even undergo deactivation whilst inside the
matrix [10, 11]. Bacteria in biofilms are also less
susceptible to the action of antibiotics, which
may contribute to the development of chronic
infections and relapses [12, 13].
Several studies have described the presence of
biofilms formed in infected root canals [14–16].
Biofilm structures have been reported to be
formed alongside the canal walls, inside dentinal
tubules, apical deltas and periapical areas [1–3].
The presence of these microbial structures has
been associated with different clinical states
including post-treatment endodontic infections
[14–16].
Of importance is to understand the biological
basis of biofilm formation as it is possible that
various microbial genetic regulatory pathways
involved may also play a crucial role in mechanisms of resistance to host immune defences and
antimicrobial treatment [12]. Notwithstanding
the characterization of biofilms in infected root
canals, the mechanisms behind their formation in
root canals have not been well established. As
most of the species found in root canals are also
found in the oral cavity, it is reasonable to speculate that the formation of microbial biofilms in
root canals may have similar mechanisms as oral
biofilms. Figure 3.2 depicts the main events
occurring during the formation of a biofilm.
3.2.1
Initial Adherence to Surfaces
In the oral ecosystem, the deposition of salivary
components provides a set of receptor molecules
which are primary recognized by the early colonizers, such as streptococci and actinomyces
[17]. In root canals of teeth, the presence of
plasma constituents, which increase exponentially due to inflammatory transudation, may
23
form the active conditioning film paving the way
for subsequent microbial colonization [18].
Plasma constituents, such as plasminogen, may
endow with primary receptors for adhesion on
root canal surfaces [18]. This previous hypothesis
is supported by the fact that several oral species
have an affinity to bind to plasminogen via very
specific lysine-dependent mechanisms. Among
the most common plasminogen-specific binding
receptors in oral species are enolase and GAPDH.
The conditioning film may not only influence
the initial adhesion of colonizing cells, but it will
also influence the production of signalling molecules that control cell physiology and resistance
to antimicrobials. In a recent study, it was found
that biofilms formed by root canal bacteria on
surfaces preconditioned with collagen showed
irregular architectures, which apparently also
influenced their responsiveness to the exposure
with antimicrobials [19]. Biofilms formed on
collagen-coated surfaces by Streptococcus gordonii, E. faecalis and Lactobacillus paracasei
showed a much higher resistance to NaOCl than
those biofilms formed on non-coated surfaces.
Interestingly, it was found that the levels of dehydrogenase and esterase activities of biofilm cells
which adhered to collagen-coated surfaces were
very low, a finding which may partially explain
their high resistance to antimicrobials. The metabolic downregulation of biofilm cells on surfaces
coated with collagen may give some indications
as to how the surface condition may influence
bacterial physiology and consequently resistance
to antimicrobials.
3.2.2
Secondary Colonizers
Secondary colonizers co-aggregate to adhering
cells after the first colonizers have irreversibly
adhered to the surfaces [17]. The newcomers will
form close metabolic relationships with the
adhered cells, developing microenvironments for
the establishment of bacteria with special requirements such as obligate anaerobes [17]. Bacteria
with plenty of receptors that are recognized by
many other organisms, such as fusobacteria, play
a key role in forming a link between primary
L.E. Chávez de Paz
24
Fig. 3.2 Schematic
depiction of the
temporal sequence of
biofilm formation. (a)
Clean surfaces are
coated with
environmental
molecules. (b) Pioneer
microorganisms adhere
to the conditioned
surface, utilizing
different cell-surface
interactions. (c)
Incorporation of
secondary colonizers by
adhesion to the pioneers
by utilizing different
engaging adhesins. (d)
The production of
extracellular polymeric
substance (matrix)
results in the formation
of mature biofilms
where intermicrobial
signalling and
intergeneric
co-aggregation leads to
the development of
complex communities
a
Surface
coating
b
Initial
adhesion
c
Secondary
colonization
d
Growth/
maturation
seconds
minutes
hours
days/weeks
c­olonizing species and later colonizing pathogens [17]. In infected root canals, the presence of
fusobacteria has been widely reported and has
been linked with the occurrence of cases with
most severe inflammatory symptoms [6]. In such
cases, fusobacteria were found in combination
with highly proteolytic organisms, e.g. Prevotella
and Porphyromonas. Hence, it is likely that the
surface receptors from fusobacteria promote the
colonization of these proteolytic pathogens in
root canals. A similar case is seen in microbiological screening of sites of periodontal inflammation, where fusobacteria appear just before the
pathogenic “red” complex consisting of
Porphyromonas gingivalis, Treponema denticola
and Tannerella forsythia [20].
The presence of E. faecalis in post-treatment
infected root canals has received much attention
since this is an organism that shows, among other
interesting capacities, high tolerance to alkaline
pH [21–23]. Although the majority of these observations have been made in vitro, its high tolerance
to alkaline has been clinically linked to a potential
resistance to treatment with inter-­
appointment
dressings containing calcium hydroxide [5, 7].
However, the origin of E. faecalis in infected root
canals has remained highly controversial because
this organism is not commonly found in untreated
necrotic pulps and has been until recently considered a ‘transient’ microorganism in the oral flora
[24]. E. faecalis has been isolated from teeth presenting post-­treatment infections with a prevalence
3
Aetiology of Persistent Endodontic Infections in Root-Filled Teeth
of 24% and 70% in studies utilizing traditional
culture-­
based techniques [4–7, 25, 26] and
between 66 and 77% when molecular methods
were applied [27, 28]. In a recent series of studies
[29], it was determined that E. faecalis is not
likely to be derived from the endogenous commensal flora of the gastrointestinal tract and that
even the chances for nosocomial transmission
during a root canal treatment from contaminated
high-touch surfaces in dental operatory were
slight. It was stated, however, that E. faecalis in
root canal infections are most likely food-borne
since strains from root canals and food items
shared common genotypic patterns [29].
3.2.3
Growth and Maturation
During growth and maturation of the biofilm,
the concentration of chemical signals produced
by metabolism provokes a range of phenotypic
differentiations among the species forming
microbial communities [13, 30]. These different
phenotypes trigger molecular responses that are
generated as chemical signals corresponding to
secondary metabolites, also known as quorum
sensing. The quorum sensing of microbial cells
in biofilms recognizes the proximity of cells
reaching a critical number in a limited space in
the environment and that ultimately results in
the autoinduction and synthesis of the extracellular matrix [10]. The biofilm matrix is mainly
composed of polysaccharides, proteins, nucleic
acids and lipids and is a key feature to the maturation of biofilm formation. The matrix will
constitute the backbone of the biofilm’s threedimensional structure and will allow the free
circulation of metabolites and wastes among
cells and microcolonies. The structure cohesiveness conferred by the matrix permits that the
biofilm community to respond like a mass and
behave as a group [10].
The composition of the matrix varies depending
on the bacterial species, the environmental conditions and the metabolites available. The presence
of high levels of nutrients can lead to very dense
biofilms. For instance, in oral biofilms the presence
of high levels of sucrose in the media yields very
25
dense and large biofilms [31]. This phenomenon
was explained to be due to the ability of many oral
bacteria to synthesize dextrans (including the insoluble 1,3-α-D-glucan mutan) and levans using
sucrose as a substrate. It has also been observed
that mixed biofilms grown on limited nutrients that
are then switched to a rich medium change considerably in their structural appearance [32].
3.3
Extra-radicular Colonization
Contrary to the traditional view of extra-radicular
tissues being always free of bacteria, compelling
clinical evidence now exists on bacteria forming biofilms on extra-radicular surfaces [33–36].
Although most of the studies are described as
case reports, it is reasonable to conclude from the
available information that the formation of extra-­
radicular biofilms occurs with relative frequency.
Although still unclear, the formation of extra-­
radicular biofilms seems to be a consequence of
massive infection of the root canal system associated with prolonged exposure of the canal space
to the oral environment [34]. Of interest is, however, that most cases presenting extra-radicular
biofilms are associated with sinus tracts which
may indicate inclusion of oral fluids during biofilm formation. The latter hypothesis is sustained
with the finding of calculus-like extra-radicular
biofilms [33, 34, 36]. Figure 3.3 shows a case of
maxillary right central and lateral incisors with
deficient root canal treatments and presenting
calculus-like material covering the apexes of
roots [33]. Upon clinical inspection, an open fistula was detected in the apical area of teeth 11
and 12. Both teeth were sensitive to percussion,
and the apical mucosa was sensitive to palpation.
Radiographic examination showed a large periapical lesion with a thick layer of radiopaque
material covering both root tips. Treatment
included orthograde retreatment followed by apical surgery. As it is visualized in the clinical photograph, during surgery both root tips presented a
calculus-like material covering the root surfaces.
Examination by scanning electron microscopy
(SEM) of the resected specimens confirmed the
presence of mineralized biofilms in the apexes,
L.E. Chávez de Paz
26
a
b
c
e
d
Fig. 3.3 Case presenting extra-radicular biofilm formation in the form of calculus. (a) Preoperative radiograph
shows extensive calcifications on the apex of 12 and 11.
(b) Post-operative radiograph taken after orthograde root
canal retreatment. (c) Postsurgical radiograph. (d) Clinical
photograph during surgical procedure shows the bone
defect and a dark calculus-like structure covering the apex
of teeth 12 and 11. (e) Representative scanning electron
microscopy (SEM) micrograph showing clusters of cells
forming extra-radicular mineralized biofilm structures.
Case is published in [33]
where cells were embedded in mineralized matrix
in a very similar fashion as supra- or sub-gingival
calculus. One of the possible explanations for the
occurrence of these mineralized structures is the
long-standing sinus tract which may have allowed
passage of fluids from the oral environment,
including minerals and salts that could form these
solid mineralized masses.
3.4
Host-Microbe Interactions
The presence of biofilms in root-filled teeth leads
to a chronic inflammatory reaction in the periapex which is characterized by the proliferation of
macrophages, lymphocytes and plasma cells [37,
38]. Chronic apical lesions become encapsulated
in collagenous connective tissue which is stimulated
3
Aetiology of Persistent Endodontic Infections in Root-Filled Teeth
by the upregulation of connective tissue growth
factors (TGF-β) [37, 38]. In this chronic phase
which can remain symptomless for long periods
of time, activated T cells produce cytokines that
downregulate the output of pro-­
inflammatory
cytokines (IL-1, IL-6 and TNF-α), leading to the
suppression of osteoclastic activity and reduced
bone resorption [37, 38]. Upon a secondary invasion of microorganisms, the lesion can spontaneously turn into an acute inflammatory reaction
by rapid recruitment of PMNs, a feature that is
characterized by a rapid restitution of apical
bone resorption. And the previous silent clinical
situation may suddenly turn into a symptomatic
phase.
The chronic inflammatory lesion associated
to failed-root canal treatments is in many cases
associated to the presence of well-developed
fibrous capsules consisting of dense collagenous
fibres that are firmly attached to the root surface
[37, 38]. These chronic lesions, also known as
granulomas, do not normally harbour microorganisms but only in special cases: (a) acute
inflammatory phase [39], (b) periapical actinomycosis [40–42], (c) transient contamination
during root canal instrumentation [43, 44] and
(d) infected periapical cysts with cavities open
to the root canal [45]. The main function of the
apical granuloma is thus to contain and encapsulate the advancement of the infection. In the
lumen of the granuloma, macrophages, including
blood-­derived macrophages, epithelioid cells and
multinucleated giant are aimed to kill bacteria.
However, complete eradication of bacteria does
not always occur. As it has been described in few
case reports [40–42], species of Actinomyces and
Propionibacterium (formerly Arachnia) have
been found forming clusters within the lumen
of the granulation mass. Although the mechanisms behind clustering formation are not clear,
it may seem that clustering occurs as a microbial strategy to persist within the granuloma and
perhaps to reactivate and escape under special
circumstances.
The survival of Mycobacterium tuberculosis
in granulomatous tissues is a good example for
understanding the mechanisms behind bacterial
survival within a granuloma. It has been proposed
27
that the unfavourable conditions inside the granuloma, such as nutrient limitation and low oxygen tension, trigger the metabolic downshift of
M. tuberculosis into dormancy [46]. Of critical
interest is, however, that under specific circumstances M. tuberculosis re-establishes its metabolic and replicative activity by the activation of
a complex cascade of enzymes regulated by
resuscitation-promoting factors (Rpf) [46].
Although it has not been established if Rpf
orthologs are present in Actinomyces or other
endodontic pathogens, the reactivation from a
dormant state seems to be an interesting hypothesis to clarify the occurrence of exacerbations of
chronic infections. This hypothesis was tested in
an experimental study, where biofilm cultures of
S. anginosus and L. salivarius were forced to
enter a state of dormancy by exposing them to
nutrient deprivation [47]. Dormant cells were
then forced to reactivate by exposure to fresh
nutrients, but even after 96 h the cells remained
metabolically inactive. This observation highlights the null physiological response of dormant
cells even in the presence of fresh nutrients,
which may act as a mechanism to resist further
disturbances.
3.5
Resistance vs. Tolerance
The increased survival rate of bacteria is one of
the fundamental causes of endodontic treatment
failure and because chronic infections present as
a complicated challenge [1–3]. In order to understand the mechanisms by which bacteria survive,
it is important to differentiate two main concepts:
resistance and tolerance. As it is illustrated in
Fig. 3.4, resistance comprises the mechanisms
that are specifically exerted by bacteria in the
presence of antimicrobials and that are aimed to
inactivate them. Common resistance mechanisms
include physical prevention of the antimicrobials
from reaching its target (e.g. low diffusion
through the biofilm matrix), alteration of the target such that it is no longer recognized by the
antimicrobial (e.g. modification of cell receptors)
and inactivation of the antibiotic properties to
obstruct its ability to interact with its target [48].
L.E. Chávez de Paz
28
Exposure to
antimicrobials
Cell death
Resistance
Tolerance
Fig. 3.4 Schematic illustrating the differences between
microbial resistance and tolerance. (a) Cell death is normally expected after treatment of a bacterial population
with an antimicrobial. (b) Resistance is regulated by
mechanisms that are specifically exerted by bacteria to
restrain the interaction of antimicrobials with cells. (c)
Tolerance comprises mechanisms of phenotypic adaptation in the presence of antimicrobials upon interaction
with the cells
Tolerance is fundamentally different as it does
not affect the ability of the antimicrobial to interact with its target. Although the molecular events
that lead to antimicrobial tolerance in bacteria are
not yet clear, the mechanisms that are involved
seem to be mainly controlled by phenotypic
adaptive processes (e.g. metabolic downregulation or adaptation) [48]. Phenotypic tolerance is
elicited as a result of environmental factors (such
as nutrient deprivation and pH changes) that
affect antimicrobial-induced killing, whereas
genotypic tolerance can arise from specific
genetic changes within the tolerant bacteria [48].
3.5.1
esistance of Endodontic
R
Microorganisms
The killing effect of antimicrobials (individually
or in combinations) has been thoroughly evaluated in microbiological research in endodontics.
Although most of the studies have been performed
ex vivo, it is consensus that the use of different
chemicals with antimicrobial properties for disinfection may be to different extents effective to
affect the root canal microbiota [49, 50].
However, it is clear that a portion of the microbiota, especially those that are deep-seated in hard-­
to-­reach areas and forming multispecies biofilm
communities, may resist and remain viable after
treatment with antimicrobials [14, 36].
A key feature on antimicrobial resistance is
the differences between cells growing in planktonic or in biofilm conditions. In planktonic cultures, antimicrobials can gain direct access to
bacterial cells, whereas in biofilms they encounter diffusion-reaction limitations through the
matrix so that they hardly can reach the deepest
layers of the biofilm in their active form [12, 13].
For example, a recent study showed that biofilms
formed by root canal isolates L. paracasei and E.
faecalis that were exposed to chlorhexidine, cells
in the upper layers of the biofilms, were more
affected than those in the deeper layers [19]. A
similar finding has also been reported to occur in
dental plaque biofilms in which chlorhexidine
showed the highest antimicrobial effect in the
outermost layers of dental plaque but failed to
kill cells in the deeper layers of the biofilms [51].
3.5.2
olerance of Endodontic
T
Microorganisms
The post-treatment microbiota comprises a subset of species that have a high tolerance towards
environmental changes provoked by antimicrobials, lack of nutrients and the host immune cells.
In this case, tolerance is distinguished by the
capacity of bacteria to adapt their phenotype in
order to endure changes in environmental conditions [13]. Although most of the mechanisms of
tolerance by root canal bacteria have not been
clarified, it seems that some mechanisms maybe
coordinated concurrently from a main general
stress response with the interplay of various regulatory processes taking place at the same time
[21, 22].
One of the most studied characteristics among
bacterial isolates remaining in root canals after
3
Aetiology of Persistent Endodontic Infections in Root-Filled Teeth
treatment is their ability to tolerate an alkaline
environment, which is provoked after the application of CaOH2 as an inter-appointment medication. Some members of the post-treatment
microbiota, such as E. faecalis, are well known to
have an intrinsic tolerance to alkaline, e.g. by
exertion of proton pumps [23], or release of stress
proteins [52]. Interestingly, it has been recently
demonstrated that tolerance to alkaline may be
intrinsic for a greater portion of the original root
canal population [53]. In this study by Lew et al.,
more than 60% of untreated infected root canals
harboured alkaline-tolerant bacteria with most of
them being Gram-positive organisms [53]. From
a general perspective, however, the tolerance of
root canal bacteria to alkaline stress has been
observed to be regulated by extracellular release
of housekeeping enzymes, such as phosphocarrier HPr, the heat shock chaperone DnaK, FBA
and GAPDH [22]. Although the physiological
role of these housekeeping enzymes outside the
cell is unknown, most of these enzymes have also
been found to be associated with the bacterial
response to other similar environmental stresses
such as acid challenge [54]. Interestingly, a recent
transcriptomic study observed that during alkaline stress, E. faecalis expressed as much as 613
genes. From these newly expressed genes, 211
genes were found to be differentially upregulated, and 402 genes were differentially downregulated [55]. Fifteen of these upregulated genes
were found to be involved in amino acid transport, a characteristic that gives clear insights into
the metabolic demands of E. faecalis when
exposed to alkaline stress.
The ability to tolerate an environment with
scarce or limited nutrients demands an efficient
control of the mechanisms that regulate the nutritional needs of root canal bacteria. These nutrient-­
adaptive capabilities have been observed in some
oral bacteria that coincidentally have been also
isolated from cases with persistent root canal
infections. For example, in the saccharolytic
organism Streptococcus oralis, a number of proteolytic enzymes have been found to be upregulated upon exposure to carbohydrate-deprived
environments [56]. This particular ability in S.
oralis to digest proteins could be considered as
29
an advantage for their survival in the oral community at the times of carbohydrate famine.
Similar patterns have been found also for other
oral bacteria where complementary patterns of
glycosidase and protease activities are able to
degrade glycoproteins in a synergistic manner
[57]. These complex metabolic patterns have
been proposed to play a role in the catabolism of
glycoproteins such as mucins from saliva [58] or
plasminogen from serum [18].
Specific stress-regulator mechanisms such as
‘the stringent response’ may be involved in the
regulation of the nutritional needs of root canal
bacteria [59]. The stringent response encompasses a massive switch in the transcription profile of bacteria, which is coordinated by the
alarmones guanosine tetraphosphate (ppGpp)
and guanosine pentaphosphate ((p)ppGpp) [59].
In E. faecalis, these alarmones play an important
role in low-nutrient survival [60]. Furthermore,
the alarmone system (p)ppGpp has also a profound effect on the ability of E. faecalis to form,
develop and maintain stable biofilms [60]. These
improved understandings of the alarmone mechanisms underlying biofilm formation and survival
by post-treatment organisms such as E. faecalis
may facilitate the identification of pathways that
could be targeted to treat chronic root canal
infections.
In general, basic research on mechanisms of
resistance and tolerance in combination with
clinical studies is expected to reveal general
mechanisms of microbial survival in order to provide a clearer understanding of the pathogenesis
of post-treatment infections and to develop more
efficient ways to treat them.
Take-Home Lessons
• Microorganisms surviving in endodontically treated root canals remain assembled in biofilm communities and are the
main cause of apical periodontitis in
root-filled teeth.
• In biofilms a number of factors will play
a role in microbial survival such as the
low diffusion of antimicrobial agents,
L.E. Chávez de Paz
30
the entry of cells into low-energy states,
differentiation into tolerant subpopulations and the expression of biofilm-­
specific antimicrobial resistance genes.
• Microbial resistance and tolerance
to antimicrobials are multifactorial,
complex and very difficult to predict
in multispecies communities where
more than one mechanism plays a part
simultaneously.
• Further research is required as for most
of the root canal bacteria we do not yet
have a minimal view of the regulatory
processes involved in biofilm formation,
phenotypic adaptation or antimicrobial
tolerance.
micro-organisms, many of which are
normal oral commensals’.
• Nair PN. Pathogenesis of apical periodontitis and the causes of endodontic failures.
Crit Rev. Oral Biol Med. 2004;15:348–81.
‘A thorough and comprehensive review
of different histo-­pathological aspects of
apical periodontitis’.
• Svensäter G, Bergenholtz G. Biofilms in
endodontic infections. Endod Topics.
2004;9:27–36. ‘A pioneer review paper
on microbial biofilms in endodontics,
which by means of sound biologically-­
based hypotheses introduces the biofilm
concept in endodontics’.
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4
Consequences
Fredrik Frisk and Thomas Kvist
Science is the knowledge of consequences, and dependence of one fact upon another.
Thomas Hobbes (1588–1679). English philosopher
Abstract
Persistent or emerging apical periodontitis is a common finding in root-­
filled teeth. The consequences thereof may have implications for the
patient in terms of pain, tooth loss, spread of infection and additional
costs. However, inconclusive data from several studies also suggests systemic effects of apical periodontitis. Obviously, these pathologies will correspondingly influence the everyday work of dentists. Also, it may have
consequences for society and third-party payers. From a cost-benefit point
of view, it is not unequivocal which should be the treatment of choice
when a root-filled tooth is diagnosed with apical periodontitis.
4.1
Introduction
Chapter 2 thoroughly reviewed the incidence and
prevalence of apical periodontitis in root-filled
teeth. From this it stands clear that, even though
F. Frisk, DDS, PhD (*)
Department of Endodontology,
Institute for Postgraduate Dental Education,
Jönköping, Sweden
Department of Endodontology, Institute of
Odontology, The Sahlgrenska Academy,
University of Gothenburg, Göteborg, Sweden
e-mail: fredrik.frisk@rjl.se
T. Kvist, DDS, PhD
Department of Endodontology,
Institute of Odontology, The Sahlgrenska Academy,
University of Gothenburg, Göteborg, Sweden
e-mail: kvist@odontologi.gu.se
© Springer International Publishing AG 2018
T. Kvist (ed.), Apical Periodontitis in Root-Filled Teeth,
https://doi.org/10.1007/978-3-319-57250-5_4
there may be many reasons to question the exact
numbers in single studies, a great many root-­
filled teeth present with signs of apical periodontitis. Considering the great number of root-filled
teeth in populations with access to dental care,
the condition is found in every other adult. In this
chapter we will scrutinize the consequences of
apical periodontitis in root-filled teeth.
4.2
ifferent Types of
D
Consequences and Different
Stakeholders
A fact may have different consequences and
affect different parties. Three main categories of
consequences without clear boundaries between
them may be identified in relation to apical periodontitis in root-filled teeth: biological, psychological and economic. Obviously, it seems most
33
F. Frisk and T. Kvist
34
important to investigate the consequences for
those directly affected by the condition, the
patients. However, also their doctors, the dentists, will be affected, since the situation is supposed to be handled with in some way or the
other. Thirdly, also third-party payers like reimbursement organizations, insurance companies
or public and tax-­funded health organizations
are affected by apical periodontitis in root-filled
teeth. In the following we will discuss the different categories of consequences from different
point of views.
4.3
Consequences for Patients
4.3.1
Biological
4.3.1.1 Persistent Pain
Surprisingly little is known about the frequency
of pain from root-filled teeth. From the obtainable data in follow-up studies from university or
specialist clinics, in a systematic review, the frequency of persistent pain >6 months after endodontic therapy was estimated to be 5% [1]. In
this context it is also important to point out that a
painful condition associated with a root-filled
tooth not necessarily is due to the presence of
apical periodontitis [2, 3].
4.3.1.3 Local Spread of Disease
It is well known that odontogenic infections
may have the potential for life-threatening
spread to other parts of the body [6]. In a study
from the United States approximately 61,000
hospitalizations of patients were primarily
attributed to periapical abscesses during a
9-year study period [7]. The mortality was
reported to be approximately 1‰ (66 patients).
In a study from Finland, Grönholm et al. [8]
evaluated clinical and radiological findings in a
group of 60 patients with hospital stay due to
periapical periodontitis. They found that unfinished root canal treatment was the major risk
factor for hospitalization. Root-­filled teeth with
apical periodontitis were the source only in 7
(12%) of the 60 cases. It has been calculated
that the amount of root-filled teeth only in
United States is about 420 million [9] and that
approximately 36% of these present with signs
of apical periodontitis [10]. Pooling the information from these different sources would
result in an estimated risk of severe event,
requiring hospitalization, because of a rootfilled tooth with apical periodontitis to be
approximately 1 in 200,000 on a yearly basis.
4.3.1.4 Loss of Tooth
Two longitudinal studies in Scandinavian populations found that 12–13%, respectively, of the
4.3.1.2 Flare-Ups of Asymptomatic
teeth that were root filled at the base-line examiLesions
nation were extracted at follow-up approximately
The incidence and severity of exacerbation of 10 years later [11, 12]. In the Danish population,
apical periodontitis from root-filled teeth have it was found that teeth with apical periodontitis
met only scarce attention from researchers. A low (non-root filled and root filled) had a six times
risk of painful exacerbations (1–2%) was reported higher risk of being lost than teeth without apical
from a cohort of 1032 root-filled teeth followed periodontitis [13]. In a selected Swedish populaover time by Van Nieuwenhuysen et al. [4]. In a tion, the 20-year survival rate of root-filled teeth
report from a university hospital clinic in was 65% [14]. The finding of apical periodontitis
Singapore where 127 patients with 185 non-­ at baseline was among variables associated with
healed root-filled teeth were recruited [5], flare-­ low odds for tooth survival. However, it is diffiups occurred only in 5.8% over a period of cult to tell whether the observed correlations are
20 years. Less severe pain was experienced by causative or a consequence of biased selection of
another 40% over the same time period. The inci- cases for extraction. Observations from other
dence of discomforting clinical events was sig- studies suggest that other causes than apical perinificantly associated with female patients, odontitis such as periodontal disease, caries or
treatments involving a mandibular molar or max- root fracture are frequently present when root-­
filled teeth are extracted [15, 16].
illary premolar and preoperative pain.
4 Consequences
4.3.1.5 Systemic Effects
The possible association between systemic diseases and inflammatory processes of endodontic
origin has been debated for more than 100 years.
However, evidence is poor, and only a few scientific studies of good quality are available [17].
A possible correlation between apical periodontitis and cardiovascular disease (CVD) and
coronary heart disease (CHD), respectively, has
been of certain focus. One study found an association between apical periodontitis and CHD in
middle-aged and younger men (<40) over a
32-year period [18]. In one cross-sectional study,
an analysis of female patients demonstrated no
increased risk of CHD among those with apical
periodontitis, after adjustment for established risk
factors [19]. Yet another study comprised analysis
of a large number of health professionals receiving medical care [20]. A weak association to CHD
was reported with respect to individuals with one
or two root fillings.
One case-controlled clinical trial showed a
positive association between the number of
inflammatory lesions of endodontic origin with
acute myocardial infarction or unstable angina
compared with healthy controls [21]. One study
evaluated whole-body computed tomography
examinations of 531 patients retrospectively. The
atherosclerotic burden of the abdominal aorta
was quantified using a calcium scoring method.
Chronic apical periodontitis correlated positively
with the aortic atherosclerotic burden. In regression models, apical lesions in teeth without endodontic treatment were found to be an important
factor but so did not apical radiolucencies in root-­
filled teeth [22]. One study investigated whether
an association between chronic oral infections
and the presence of an acute myocardial infarction exists. The results showed that patients, who
have experienced a myocardial infarction, had
more missing teeth and a higher number of
inflammatory processes of endodontic origin
than healthy individuals [23]. In a retrospective
study the presence of apical periodontitis and
root-filled teeth was associated with long-term
risk of incident cardiovascular events, including
cardiovascular-related mortality [24]. Finally, in
a pair-matched, cross-sectional designed study,
35
subjects with apical periodontitis were more
likely to have CVD than subjects in the final
adjusted logistic regression model [25].
Other systemic diseases that have attracted
attention are diabetes mellitus, chronic liver disease and different types of blood disorders [17].
At present time the association between endodontic disease and different systemic conditions
rests on shaky scientific ground. However, the
thinkable biological mechanisms behind a link
are present [26]. It is obvious that relationships
between endodontic infections and general health
and well-being should be in focus of future
research in endodontology.
4.3.2
Psychological Consequences
The psychological effects include aspects of
knowledge, beliefs, attitudes, values, preferences,
quality of life and satisfaction. Quality of life is
concerned with the degree to which a person
enjoys the important possibilities of life [27].
Surprisingly few studies have addressed these
“patient-centred” outcomes of endodontic treatments [28]. Disease of pulpal origin negatively
affects quality of life primarily through physical
pain and psychological discomfort, and root canal
treatment results in distinctive improvement [29].
The impact on daily life activities (eating,
speaking, sleeping, contact with people, etc.) by
painful exacerbations of persistent periapical
lesions in root-filled teeth was reported in the
previously mentioned study from Singapore [5].
Among the 127 patients with apical periodontitis
in a root-filled tooth recruited for the study only
33 patients (38 teeth) had experienced some kind
of impact over a period 38 years. But only five
patients reported substantial impact.
The attitudes towards asymptomatic persistent
lesions among patients affected have only met
scarce attention. In two studies value judgements
towards an asymptomatic root-filled tooth with a
periapical lesion were investigated by methods
used in the context of expected utility theory [30,
31]. In both studies elicited subjective values
towards asymptomatic apical periodontitis and
root-filled teeth showed great variation.
F. Frisk and T. Kvist
36
4.3.3
Economic Aspects
A great many teeth with pulpitis and apical periodontitis, even in countries with well-developed
dental care, often do not come under dental treatment. They remain unrecognized, because they
are asymptomatic or are considered among the
ordinary discomforts of daily living. Or, the
patient may be suffering from both pain and other
symptoms for a prolonged period of time but
because of economic limitations has not been
able to seek dental care [32]. Cost is a significant
barrier to receiving dental care and a very important factor in patients’ treatment choices. The
“willingness to pay” for root canal treatment in
order to save an asymptomatic nonvital lower
first molar was studied in a population of 503
patients in England [33]. Only, 53% of the sample wished to save the tooth with a mean “willingness to pay” of £373. The variation in
willingness to pay was found to be substantial
and influenced by income. Initial cost may capture patients’ attention, but that is only the beginning. The original cost of tooth retention through
root canal treatment and restoration is usually
considered to be lower than tooth replacement
using implants or fixed dental prostheses [34].
However, the lifetime cost model for different
options should also include treatment failures. In
a cost-effectiveness model from the United
Kingdom, regarding a maxillary incisor, it was
calculated that saving a tooth by root canal treatment, followed by non-surgical retreatment if
indicated, was cost-effective. However, surgical
retreatment was not found to be cost-effective
[35]. On the other hand, an American cost-­
effectiveness modelling study, for a root-filled
treated molar in need of re-intervention, ranked
surgical retreatment, non-surgical retreatment,
replacement using a fixed dental prosthesis and
replacement using an implant, from the greatest
to smallest cost-effectiveness [36]. There are several problems involved in using these data in a
clinical situation for an individual patient’s point
of view. First of all, the calculations are highly
sensitive to different care providers’ fees for the
interventions put into the algorithms. Secondly, it
is possible that the benefits available under the
prevailing dental care reimbursement system
encourage one of the options at the expense of the
other regardless of cost-effectiveness in the long
term. Thirdly, cost-effectiveness analyses compare relative costs and outcomes but do not take
into account individual patient values. One can,
with good reason, assume that individuals who
already paid for root canal treatment once are
reluctant to pay for retreatment, in particular, if
the tooth is asymptomatic. Data from the many
epidemiological studies, showing that root-filled
teeth with persistent apical periodontitis are very
common, suggest that patients and their dentists,
in many cases, assess the cost-benefit ratio to be
too low to undertake any operation whatsoever.
4.4
Consequences for Dentists
The high prevalence of apical periodontitis
among adult patients is a challenge for dentists in
several ways. In the following, some important
issues, from the dentist’s point of view, will be
briefly mentioned. Most of these aspects are
more thoroughly addressed in the other chapters
of this book. Here, some aspects not covered
elsewhere are discussed.
4.4.1
Diagnosis
When a patient presents with a root-filled tooth
causing pain and swelling or chronic clinical
findings in the form of redness, tenderness and
fistulas, it is usually relatively straightforward to
diagnose a persistent, recurrent or arising apical
periodontitis. However, the most common situation is that the root-filled tooth is both subjective
and clinically asymptomatic but an X-ray reveals
that bone destruction remains. It is difficult to
determine how long is the time that may be
required for such a healing process in a particular
case. The diagnosis of periapical tissues based on
intra-oral radiographs has repeatedly unmasked
considerable inter- and intra-observer variation.
Besides the time aspect and observer variation,
there is also a problem of determining what
should be considered as a sufficient healing of
4 Consequences
bone destruction to constitute successful endodontic treatment. And as a consequence also
what establishes a “failure” and hence an indication for retreatment is far from unambiguous.
4.4.2
Liability
According to the limited data available in the literature, claims concerning endodontics are common among dental professional liability cases
[37, 38]. The high prevalence of root fillings of
poor quality, as pointed out in numerous studies,
makes this hardly surprising. However not all
claims are justified. All healthcare, including
endodontics, need to weigh the benefits of various measures against the risks. The goal of all
dental care is of course that it will be of benefit
to those who receive it. But sometimes the procedures per definition are resulting in injuries or
damage. Some “damage” is planned, as when the
affected tooth is opened by removal of hard tissue in order to get access to the root canal system. Unnecessary injuries may occur as a result
of incompetence, negligence or by a single mistake. Even the most skilful, well-educated and
experienced dentist can make mistakes sometimes. Some endodontic treatments can also be
very complicated, with more built-in risk for
complications than others. These injuries are
regrettable but are an inherent risk of endodontic
procedures that one can seek to reduce over time
through improved treatments, better education
and more hands-on instruction. But injuries that
occur because of carelessness, incompetence or
because the caregiver has not complied with in
the scientific and technological developments in
the profession are avoidable in a completely different way and cannot be viewed as acceptable.
And as a result of quality deficiencies in the primary endodontic treatment, a suspicion or accusation of malpractice may emerge when a
persistent apical periodontitis is diagnosed in a
root-filled tooth.
When treating diseases of infectious and
inflammatory disease emanating from the pulp,
unsuccessful outcome may occur despite professional excellence in every detail. It is of p­ aramount
37
importance to inform about the possible risks of
the treatment procedures and explain that treatment may not always lead to a successful result,
even though it is performed in accordance with all
the rules. This should be a part of the informed
consent procedure. A malpractice claim might be
perceived as a criticism of the dentist’s competence and skills but also as a sign of a downfall in
communication with the patient.
If a root canal treatment “failure” is diagnosed
despite a reasonable high-standard treatment procedure, and the patient understands and accepts
the situation, there is also little to argue about.
The problem is limited to a decision-making
problem if and how the pathology should be
treated.
If both the patient and dentist are aware and
agree about that the initial endodontic treatment
was of poor quality, it seems appropriate to find a
way forward to rectify what can be corrected
while the patient is held economically indemnified. Depending on which country, different laws
and practices set the framework for possible
insurance claims, compensation claims or other
legal procedures.
Sometimes when a patient switches dentist,
the new dental team discovers that previously
performed dental care is not of good quality. In
our particular branch of dentistry, this is almost
the rule rather than the exception when a patient
is referred from a general dental practitioner to a
specialist in endodontics, especially when it
comes to root-filled teeth. The patient, however,
may be completely unaware of the quality deficiencies that exist. Perhaps it will be obvious,
also for the patient, when the examination and
possible treatment by the specialist is starting.
The question of how to act in such a situation
is difficult. Based on the principle of informed
consent and patient’s right to autonomy in healthcare, it seems, at first, as obvious quality defects
in prior treatment should be mentioned. However,
diagnosis, treatment selection and execution in
endodontics are not an exact science. It is p­ ossible
that circumstances that the patient has forgotten
or chosen to hide would put the poor quality of
treatment in a new light. Furthermore, many
­endodontic specialists’ practice depends on good
F. Frisk and T. Kvist
38
relations with the dentists who provide them with
the referrals. A good way can be to work to make
it natural to contact each other in a dialogue about
possible mistakes, incorrect routines and constructive suggestions for changes for the better in
the future. Of course, each dentist is responsible
for ensuring that the patient’s interests are put
first. However, the dentists who are considering
to criticize a colleague before a patient or to participate in any legal process of insufficient quality of treatment performed should consider the
conditions carefully. May the poor quality be
explained by the different ways to interpret treatment needs and outcome or is it obvious that the
treatment did not live up to current standards.
4.4.3
eed for Training
N
and Armamentarium
For everyone who attended in congresses and
conferences on endodontics in recent years, it is
obvious that there are a variety of instruments
and equipment to the field of endodontic retreatment. It is also offered a variety of courses, both
theoretical and hands-on to learn how these
instruments are used. Development in the area
has been almost explosive in the last 20 years.
There are also a number of published books that,
more or less in detail, describe how to perform,
both surgical and non-surgical, endodontic
retreatment procedures. The range is so wide that
it is difficult even for a specialist in the subject
endodontics to keep up with developments and
have an overview of available armamentarium.
For a general dentist, it seems almost impossible.
The situation is particularly pronounced for surgical retreatment procedures where the use of the
operating microscope, ultrasonic technology and
modern cements, the MTA and similar, seems to
be a prerequisite for achieving the good results of
the operations performed. Parallel to this development there is a wider exposure of all practitioners to lectures and advertising pertaining to
implant placement. It is therefore barely surprising that general dentists and dental specialists
within other areas quite widely opt out retreatment options in favour of solutions with implants,
while endodontists suggest tooth retention by
non-surgical or surgical retreatment.
Bigras et al. [39] compared the clinical
decision-­making choices of general dentists to
prosthodontists, endodontists, oral surgeons and
periodontists when presented with patient scenarios where a root-filled tooth was presented
with a need for intervention. When asked whether
to endodontically retreat or replace the specific
tooth with an implant, the retreatment option was
selected by 96% of the endodontists, 48% of the
general dentists, 36% of the prosthodontists, 31%
of the oral surgeons and 24% of the periodontists.
Similar to Di Fiore et al. [40], there was an
increase in the selection of implants, for all participant groups, as the prosthetic and endodontic
complexities of the clinical situations increased.
On the other hand, if a clinician has endeavoured to develop particular skills in a limited field
of dentistry, like modern endodontic surgery,
there is a tendency for selecting this treatment
option whenever found appropriate. Hardly surprising, von Arx et al. [41] settled that apical surgery was the most frequently made treatment
decision in teeth referred to a specialist in apical
surgery.
4.4.4
Need for Specialists
Based on the comparison between studies of the
outcome of root canal treatment performed by
specialists and supervised dental students and, on
the other hand, epidemiologic surveys of various
populations, it is generally established that there
is a discrepancy regarding treatment outcome
between what it is possible to achieve in certain
clinical settings and what is actually achieved in
daily practice [42]. In order to improve the overall results of endodontic treatment rate and for
the benefit of patients in general dental practice,
it has been suggested that difficult cases should
be referred to dentists with advanced knowledge
and training [43–45].
However, surveys of referral-based endodontic practices have revealed that the major proportion of cases seized consists of symptomatic teeth
and teeth in need of re-intervention [46, 47].
4 Consequences
4.5
onsequences for the Third
C
Party
Dentists in most countries have been trained at
universities or dental schools. Usually training
takes several years and is considered demanding. The professional role of a dentist is usually surrounded by high prestige. Knowledge
and skills in endodontology are within the
compulsory scope of each training to become
a dentist. To be able to diagnose pulpitis, pulp
necrosis and apical periodontitis and to perform root canal treatment are an essential
part of dentistry because diseases of the tooth
pulp and periradicular tissues are common.
Furthermore, these, many times, painful conditions are common reasons that patients seek
out dental care.
From any society’s point of view, it is a fundamental desire that expertise in this particular field
of dentistry should be possessed by dentists.
However, studies continue to show poor technical standards of root canal treatment and high
frequency of postoperative disease [10]. Other
studies indicate that many general practitioners
lack sufficient knowledge of the fundamentals of
endodontology [48], that they often are overlooking basic principles when performing root
canal treatment [49] and that high levels of stress
and frustration and an overall sense of lack of
control are reported in relation to root canal
treatment [42].
A limited number of countries have recognized endodontics as a specialty. It is generally assumed that specialists provide better
outcomes than general practitioners. This prevailing opinion is based on the constantly
repeated finding that cross-sectional epidemiological studies which reveal high frequencies of apical periodontitis in root-filled teeth
have been reported [10], while follow-up
studies of root canal treatments performed in
specialist and student clinics exhibit substantially lower figures of persisting apical periodontitis [50]. However, only a very limited
number of direct comparisons are available
[29, 50]. The substantial variation in the study
designs both between the cross-sectional
39
studies and c­ linical studies and within the different types of studies warrants a critical
appraisal of this notion [51].
Also, the cost-effectiveness aspects of root
canal treatment compared to other solutions have
only been sporadically investigated [35].
What further makes it difficult for the community and third parties is the ambiguity among
academic representatives of endodontics not
completely agreeing on what should constitute a
successful treatment outcome (see Chap. 5:
Diagnosis).
There is no doubt that the vast proportion of
endodontic procedures will continue to be
undertaken by general dental practitioners.
Furthermore, it seems reasonable to assume
that even in the advent of better technical
skills, more advanced technology and wiser
clinical decisions, root canal treatments will
continue to save many teeth that otherwise
would have been extracted but also that many
of these will exhibit signs of persistent apical
periodontitis.
The cost-effectiveness of retreatment procedures has been questioned [52], and from a
third-­
party payer’s perspective, the willingness to pay for further interventions if root
canal treatment is “not successful” may come
to an end.
Take-Home Lessons
• Apical periodontitis in root-filled
teeth may under unfavourable circumstances lead to severe local symptoms
and also that chronic infections may
have adverse consequences for general health.
• Dentists are affected since the condition
is causing challenges both in terms of
diagnosis, decision-making and therapeutic interventions.
• Third-party payers and other stakeholders are also affected because the
state is widespread and often appears to
be indirectly caused by low quality of
treatment.
F. Frisk and T. Kvist
40
Bench-Mark Papers
• Pak JG, Fayazi S, White SN. Prevalence
of periapical radiolucency and root canal
treatment: a systematic review of crosssectional studies. J Endod. 2012;38:1170–
6. The purpose of this study was to conduct
a systematic review and meta-analysis of
the prevalence of periapical radiolucency
and nonsurgical root canal treatment.
Thirty-three articles were included. Most
patient samples represented modern populations from countries with high or very
high human development indices. Meta-­
analysis was performed on 300,861 teeth.
Of these, 5% had periapical radiolucencies, and 10% were endodontically
treated. Of the root filled teeth, 36% had
periapical radiolucencies. The prevalence
of periapical radiolucency was broadly
equivalent to one radiolucency per
patient. The prevalence of teeth with root
canal treatment was broadly equivalent to
two treatments per patient.
• Nixdorf DR, Moana-Filho EJ, Law AS,
McGuire LA, Hodges JS, John
MT. Frequency of persistent tooth pain
after root canal therapy: a systematic
review and meta-analysis. J Endod.
2010;36:224–30. In this review the core
patient-­oriented outcome of persistent
pain present > or = 6 months after endodontic treatment, regardless of etiology, after endodontic treatment was
evaluated with data from 26 articles. A
total of 5777 teeth were included, but
only 2996 had follow-up information
regarding pain status. The frequency
persistent tooth pain after endodontic
treatment was estimated to be 5.3%,
with higher report quality studies
suggesting > 7%.
• Khalighinejad N, Aminoshariae MR,
Aminoshariae A, Kulild JC, Mickel A,
Fouad AF. Association between systemic diseases and apical periodontitis.
J Endod. 2016;42:1427–34. The rela-
tionships between systemic diseases and
periapical microbial infection was systematically reviewed. Sixteen articles
were identified and included. The overall quality of the studies and the risk of
bias were rated to be moderate. Only
three studies demonstrated a low level
of bias. The results suggested that there
may be a moderate risk and correlation
between some systemic diseases and
endodontic pathosis.
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5
Diagnosis
Thomas Kvist and Peter Jonasson
Appearances to the mind are of four kinds. Things either are what they appear to be; or
they neither are, nor appear to be; or they are, and do not appear to be; or they are not,
yet appear to be. Rightly to aim in all these cases is the wise man’s task
Epictetus, 2nd century A.D.
Abstract
The diagnosis of apical periodontitis in a root-filled tooth is associated
with many difficulties. In particular, when signs of disease remain at an
X-ray but the patient and the actual tooth are otherwise free of symptoms,
the situation is cumbersome for many clinicians. In this chapter we highlight the challenges. But we also provide arguments for a diagnostic strategy that benefit of the doubt when the diagnosis is characterized of
uncertainties.
5.1
Introduction
For a root canal treatment to be considered
wholly successful in the long term, it requires not
only that the tooth is surviving, functional, and
asymptomatic. When the root-filled tooth is
examined clinically and radiographically, it
should also be free of signs of inflammation in
surrounding bony structures. If signs of inflammation persist, although presently asymptomatic,
it is likely that the root-filled tooth is containing
microorganisms and that apical periodontitis is
present.
T. Kvist, DDS, PhD (*) • P. Jonasson, DDS, PhD
Department of Endodontology, Institute of
Odontology, The Sahlgrenska Academy,
University of Gothenburg, Göteborg, Sweden
e-mail: kvist@odontologi.gu.se;
peter.jonasson@odontologi.gu.se
© Springer International Publishing AG 2018
T. Kvist (ed.), Apical Periodontitis in Root-Filled Teeth,
https://doi.org/10.1007/978-3-319-57250-5_5
5.2
Diagnostic Methods
5.2.1
Clinical Examinations
When root-filled teeth cause swelling or pain, it is
usually a sign of infection. Similarly, clinical findings at the root-filled tooth in the form of redness,
tenderness, and fistulas are signs of presence of
microorganisms. In these situations, it is usually
relatively straightforward to diagnose a persistent,
recurrent, or arising apical periodontitis.
An intraoral radiograph (see below) usually
confirms the suspicion, and diagnostic process
quite smoothly turns into a decision-making
process.
In case of a chronic sinus tract, the diagnosis
of apical periodontitis is sometimes incidental.
The observation is discovered unintentionally
and unrelated to the treatment or diagnostic procedure undertaken at the moment, for example,
during clinical examination for caries or during a
visit for preventive professional dental hygiene
43
T. Kvist and P. Jonasson
44
care. The sinus tract may exit the mucosa in
either close to or at some distance from the tooth.
When located immediately adjacent to gingival
sulcus, this can have the appearance of a deep,
narrow periodontal pocket.
5.2.2
Clinical Differential Diagnosis
There are few symptomatic pathological conditions that may be present in conjunction with a
root-filled tooth and consequently be mistaken
for persistent apical periodontitis.
However, it is important for the clinician to
be familiar with these in order to be able to
make a correct diagnosis and avoid inserting
treatments that are ineffective, costly, and at
worst harmful.
5.2.2.1 Apical Fenestration
As many as 9% of teeth have shown to have small
and window-like openings or defect in the alveolar plate of the bone, frequently exposing a portion of the root, usually located on the facial
aspect of the alveolar process [1, 2]. These findings have been confirmed by a more recent cone
beam computed tomography (CBCT) analysis on
patients with periradicular defects of endodontic
origin [3].
Pain associated with the presence of apical
fenestration may occur after root canal treatment
[4, 5]. Even slight instrumentation, irrigation or
filling beyond the apical terminus of the root
canal may irritate the periosteum and the overlying mucosa. The tooth may be spontaneously
sensitive only occasionally, but pain is usually
perceived during palpation of the area and masticatory movements. If an apical fenestration is
diagnosed, it is difficult to separate the condition
from a painful persistent ­apical periodontitis. If
an intervention is considered, surgical retreatment should be the treatment of choice. When
elevating a flap over a suspicious root tip area, the
operator hence could expect to find a root tip
without covering cortical bone. The treatment
consists of removing all pathological tissue, a
root resection, an ultrasonic tip preparation, and a
root-end filling. Special attention should be done
to foreign bodies such as pieces of the bone or
root and gutta-percha or sealer that sometimes is
found embedded in the undersurface of the flap.
Successful outcome with an asymptomatic
patient after the surgical procedure confirms the
diagnosis ex juvantibus.
5.2.2.2 Vertical Root Fracture
Patients with vertical root fractures typically
present with deep depths probing in narrow or
rectangular patterns typical of cracked tooth
lesions. But the subjective symptoms are usually
only minor pain or discomfort. Sometimes the
tooth feels a little mobile. When suspecting root
fracture in teeth with more extensive restorations,
it may be necessary to remove the fillings or
crowns for inspection and better accessibility for
probing approximal pockets.
Radiographic evidence varies. Widening of
the periodontal ligament along the whole length
of the root is a rather common feature. Only
rarely will there be visible separation of the
root segments. If there is a sinus tract combined
with the narrow, isolated periodontal probing
defect in a tooth that has had root canal treatment, with or without a post placement, the
findings are considered to be pathognomonic
for the presence of a vertical root fracture.
However, because vertical root fracture may
mimic periodontal disease or a persistent apical
periodontitis with an endo-perio lesion [6],
these cases often result in referral to a periodontist or endodontist for evaluation.
Newer methods of analysis are currently being
studied, such as cone beam computerized tomography (CBCT), in order to help identify longitudinal fractures in a nondestructive fashion [7].
However, when there is doubt about the diagnosis
and when the fracture cannot be visualized either
on radiographs or clinically despite the use of an
operator microscope, there is an indication for an
exploratory surgery.
The only predictable treatment is removal of
the fractured root or extraction of the tooth.
5 Diagnosis
45
In multirooted teeth, removal of the fractured
root may be performed by root amputation (root
resection) or hemisection.
report repeated care-seeking and numerous treatment efforts, for example, endodontic surgery,
with little or no pain relief [11].
5.2.2.3 “Pulpitis” in a Root-Filled Tooth
Missed root canal during the root canal treatment is a common indirect cause of persistent
apical periodontitis, especially in molar teeth
[8]. However, it may also be sometimes that a
tooth is painful because in missed canals or
part of canals vital and inflamed pulp tissue
remains [9].
Referred Pain from Temporomandibular
Disorder
The most common nonodontogenic reason for
pain in a root-filled tooth is probably pain originating from temporomandibular disorders where
patients’ perception of their symptoms as “tooth”
pain can be explained within the concept of
referred pain [15, 16]. Likely, the most common
sources of referred pain to the teeth are the masseter and the lateral pterygoid muscles [17].
Consequently, in lack of any objective signs of
apical periodontitis, patients experiencing a persistent pain from a root-filled tooth should be
evaluated for temporomandibular disorders.
5.2.2.4 Nonodontogenic Pain
Pain present in a root-filled tooth may sometimes
be of nonodontogenic origin. This is evidently
important because treatments and prognoses are
different.
Atypical Odontalgia (“Phantom Tooth
Pain”)
Persistent pain in lack of other clinical or radiographic (see below) signs of pathology in a root-­
filled tooth may be caused by a peripheral nerve
damage that results in neuropathic pain, a dysfunction of the somatosensory system [10–12].
The onset of the pain may have been before the
root canal treatment was performed and consequently the root canal treatment may have been
carried out following misdiagnosis. It is also possible that onset of the pain disorder is associated
with the endodontic procedures. The condition is
relatively rare [13] but challenging to dentists
because it is difficult to distinguish from pain due
to inflammation and also because inflammatory
components of pain may be present at the same
time and site. It shares many characteristics with
other chronic pain conditions, and pain perpetuation mechanisms are likely to be similar. A diagnosis should be made only after a comprehensive
examination and assessment of patients’ self-­
reported characteristics and exclusion of odontogenic [9, 14] or other nonodontogenic causes,
such as temporomandibular disorders (see
below). Traditional dental diagnostic methods do
not appear to serve well, since many patients
Trigeminal Neuralgia and Other
Neuropathic Pain Conditions
Multiple causes exist in neuropathic pain including direct nerve injury, nerve injection injury,
nerve compression injury (e.g., implant, osseous
growth, neoplastic invasion), and infection-­
inflammation damage (e.g., virus) to the nerve
itself. Fortunately, these conditions are rarely
seen in a dental office, and furthermore they
either exhibit other characteristic features, like
trigger points and refractory periods in the case
of trigeminal neuralgia, or present with concurrently other symptoms, e.g., blizzards in case of
herpes zoster infection [18].
5.2.3
Radiographic Examination
A common situation is that the root-filled tooth
is both subjective and clinically asymptomatic,
but an X-ray reveals that bone destruction has
emerged or that the original bone destruction
remains. In cases where no bony destruction
was present when root canal treatment was
completed, and in particular in cases of vital
pulp therapy, it can be reasonably assumed that
an infection has set in the root canal system.
46
For teeth that exhibited clear bone destruction
at treatment start, there must be allowed some
time for healing and bone formation to occur.
5.2.3.1 U
ncertainties in Radiographic
Diagnosis of Apical
Periodontitis
Time Passed Since Primary Root Canal
Treatment
One difficulty is to determine how long the time
that may be required for the healing process of
apical periodontitis, both in general and in the
particular case. The majority of root canal treated
teeth with bone destruction in the initial situation
shows signs of healing within 1 year [19]. In individual cases, however, the healing process can
last a long time [20, 21]. Molven et al. [22] have
reported isolated cases requiring more than
25 years to completely heal. The notion that no
absolute time limits for healing process can be
established can also be deduced from epidemiological studies [23].
Controversies of “Success” and “Failures”
of Root Canal Treatment
Besides the time aspect, there is also a problem of
determining what should be considered as a sufficient healing of bone destruction to constitute
successful endodontic treatment. And as a consequence also, what establishes a “failure” and
hence the diagnosis of persistent apical periodontitis is far from unambiguous. According to the
system launched by Strindberg [20], the only satisfactory posttreatment situation, after a predetermined healing period, combines a symptom-free
patient with a normal periradicular situation.
Only cases fulfilling these criteria should be classified as “successes” and all others as “failures.”
In academic environments and in clinical
research, these strict criteria set by Strindberg in
1956 have had a strong position.
However, the diagnosis of periapical tissues
based on intraoral radiographs has repeatedly
unmasked considerable inter- and intra-observer
variation [24] (see below).
The periapical index (PAI) scoring system was
presented by Ørstavik et al. in 1986 [25]. The PAI
T. Kvist and P. Jonasson
provides an ordinal scale of five scores ranging
from “healthy” to “severe periodontitis with
exacerbating features” and is based on reference
radiographs with verified histological diagnoses
originally published by Brynolf [26]. In this doctoral thesis, the radiographic appearance of periapical tissue was compared with biopsies. The
results indicated that using radiographs, it was
possible to differentiate between normal states
and inflammation of varying severity and that the
likelihood of a correct diagnosis improved if
more than one radiograph was taken. However,
the studies were based on a limited patient spectrum, and the biopsy material was restricted to
upper anterior teeth. Among researchers the PAI
is well established, and it has been used in both
clinical trials and epidemiological surveys (see
Chap. 2). Researchers often transpose the PAI
scoring system to the terms of Strindberg system
by dichotomizing scores 1 and 2 to “success” (=
no apical periodontitis) and scores 3, 4, and 5 into
“failure” (=presence of apical periodontitis).
However, the “cutoff” line is arbitrary. The
Strindberg system, with its originally dichotomizing structure into “success” and “failure,” has
achieved status as a normative guide to clinical
action.
As early as 1966, Bender et al. [27] suggested
that an arrested bone destruction in combination
with an asymptomatic patient should be sufficiently conditions for classifying a root canal
treatment as endodontic success. More recently
Friedman and Mor [28] as well as Wu et al. [29]
have suggested similar less strict classifications
of the outcome of root canal treatment.
The Reliability of Radiographic Evaluation
Reliability is a key feature of a diagnostic test as
results should be repeatable with high interobserver agreement. The diagnosis of periapical tissues based on intraoral radiographs is subject to
considerable intra- and interobserver variation.
One of the first studies that paid attention to the
phenomenon was authored by Goldman et al. in
1972 and 1974 [30, 31]. In the first paper, six
independent examiners evaluated 253 asymptomatic endodontically treated cases. The examiners
agreed completely on less than 50% of the cases.
5 Diagnosis
In the later, the authors studied how well some of
the first group of examiners agreed with themselves when they examined the same radiographs
6–8 months later. The somewhat s­ urprising result
was they only agreed with themselves anywhere
from 72 to 88% of the time. In a classical study by
Reit and Hollender [24], three endodontists and
three radiologists interpreted periapical conditions in radiographs of 119 root-­
filled roots.
Consensus on the presence of periapical lesion
was reached in 27% of cases classified as pathologic. The examiners agreed completely on normal periapical conditions in 37% of the cases. The
study clearly demonstrated the difficulty in defining and maintaining criteria for radiological evidence of periapical disease. In order to overcome
the problems with observer variation, different
solutions have been presented. Certainly, first of
all, the quality of the different steps in the radiographic process has to be no less than optimal.
Calibration programs for reducing interobserver variation seem to have limited effect [32].
The PAI score (see Chap. 2 and above) offers a
visual reference scale for assigning a periapical
health status.
Variation between observers could basically
be explained by their different criteria of what
should constitute reporting the presence of a periapical lesion. Such a view on the diagnosis of
apical periodontitis in root-filled teeth fits well
into the concept of “statistical decision analysis.”
Within this theory it is paradigmatic that an
observer reporting high true-positive percentage
also reports higher false-positive percentage and
vice versa. If the “true” state can be established,
in some way or the other, pairs of true-positive
and false-positive percentages can be plotted into
a Receiver Operating Characteristic (ROC)
curve. And variations between observers can be
explained by different positions on the ROC
curve. One key conclusion from applying this
theory is that false positive diagnoses will be
more frequent the lower the prevalence of the disease under study. Consequently, the best way to
uncover the relative difference between groups,
for example, in the research context, is to have a
strict criterion for the disease and report positive
findings only when absolutely certain [33].
47
Despite the avalanche of interest of CBCT in
recent years, the issue of observer variations
encountered only scarce interest from researchers
[34]. But data available from experimental and
cadaver studies [35, 36] suggests that both intraand interobservation variation are less compared
to intraoral radiographs. However, it must be kept
in mind that the use of and interpretation of
CBCT scans need particular special skills and
training.
The Validity of Radiographic Evaluation
The validity of a diagnostic test is evaluated in
terms of its ability to detect subjects with disease
as well as its capacity to exclude subjects without
disease. Uncertainties regarding the validity of
the radiographic examination [37, 38] are of concern. For obvious practical and ethical reason,
only a limited number of studies have compared
the histological diagnosis in root-filled teeth with
and without radiographic signs of pathology [26,
39, 40]. In these studies, false-positive findings
(i.e., radiographic findings indicate apical periodontitis, while histological examination does
not give evidence for inflammatory lesions) are
rare. False-negative findings (i.e., radiographic
findings indicate no apical periodontitis, while
histological examination does give evidence for
inflammatory lesions) vary in the different studies. However, it is well known that bone destruction and consequently apical periodontitis may
be present without radiographic signs visible in
intraoral radiographs [40, 41].
The advent of cone beam computed tomography (CBCT) has confirmed the findings of Bender
and Seltzer [41, 42] in recent years. In vitro studies on skeletal material indicate that the method
has higher sensitivity and specificity than intraoral periapical radiography [34]. The higher sensitivity is confirmed in clinical studies. The major
disadvantages of CBCT are greater cost and a
potentially higher radiation dose, depending on
the size of the radiation field being used. However,
one benefit of the CBCT method is that it is relatively easy to apply. It provides a three-­
dimensional image of the area of interest, an
advantage when assessing the condition of multirooted teeth. And the uncertainty of assessing
T. Kvist and P. Jonasson
48
results of endodontic treatment in follow-up using
conventional intraoral radiographic technique has
been pointed out [43]. Consequently, it has been
suggested that CBCT should be used in clinical
studies, because of the risk that conventional radiography underestimate the number of unsuccessful endodontic treatments. However, it may be
important not to jump into conclusions. One study
examined the validity of CBCT-­diagnosed apical
periodontitis with a histological examination as a
“gold standard” [35]. The authors used jaw sections from human cadavers including 86 roots in
67 teeth. All specimens also underwent histopathological examination. Different aspects of the
diagnostic accuracy of digital intraoral periapical
radiographs and cone (CBCT) were compared in
detecting apical periodontitis using histopathological findings as a reference. The study corroborated that CBCT technology is more sensitive
than intraoral radiographs, e.g., false negatives are
less frequent while a false positive only was diagnosed in one case (using the intraoral radiograph).
The study however did not specifically study rootfilled teeth, and the overall prevalence of apical
periodontitis was 67% which might explain the
overall high specificity for both methods.
One study [44] found that false-positive findings may be a potential substantial problem using
CBCT since evidently healthy teeth (vital pulps)
showed signs of apical periodontitis in CBCT but
not on intraoral radiographs. In root-filled teeth,
long-term studies are required to investigate if
healing of periapical bone destruction may take
longer than previously assumed when evaluating
results with CBCT. For example, at 1-year post
1.Technical
efficacy
2. Diagnostic
accuracy
efficacy
3. Diagnostic
thinking
efficacy
endodontic treatment follow-up, CBCT can show
persisting bone destruction, while a conventional
intraoral radiograph shows healing [45].
The Efficacy of CT and CBCT
in Endodontics
The use of a more accurate diagnostic technology
does not necessarily lead to a different course of
action or a better outcome. A hierarchical model
of efficacy has been presented as a model for
appraisal of the literature on efficacy of diagnostic
imaging by Fryback and Thornby (Fig 5.1) [46].
Demonstration of efficacy at each lower level in
this hierarchy is logically necessary, but not sufficient, to assure efficacy at higher levels. In this
model level 1 addresses technical quality of the
images. Level 2 concerns diagnostic accuracy,
sensitivity, and specificity associated with interpretation of the images. Next, level 3 focuses on
whether the information produces change in the
physician’s or dentist’s diagnostic thinking. Such
a change is a logical prerequisite for level 4 efficacy, which addresses effect on the patient management plan. The highest efficacy level studies
eventually concern effects on patient outcomes
and analyses of economic and societal costs and
benefits (levels 5 and 6). Few studies have investigated the impact of CT or CBCT on endodontics
when making a diagnosis or selecting a treatment
option, and most importantly, even lesser have
assessed the benefit to the patient of using these
imaging modalities [34, 47, 48]. As result, the evidence is still inconclusive whether the use of CT
or CBCT is warranted in the clinical decisionmaking and treatment of the individual patient.
4. Therapeutic
efficacy
Fig. 5.1 Fryback and Thornbury’s framework of the efficacy of diagnostic imaging
5. Patient
outcome
efficacy
6. Societal
efficacy
5 Diagnosis
Nonendodontic Lesions Misdiagnosed
as Apical Periodontitis
There are a number of nonendontic lesions, both
benign and malign, mimicking apical periodontitis in the radiograph. These include fibroosseous
lesions, ameloblastomas, nasopalatine duct cysts,
keratocystic odontogenic tumor, metastatic injuries, and carcinomas [49, 50]. Some of these will
present asymptomatic, whereas others will be
present with both pain and swelling. Because the
vast majority of all periapical bone lesions are
indeed due to an infection of endodontic origin,
there may be a risk of misdiagnosing those few
who are not, as apical periodontitis. It is therefore
emphasized that the clinical and radiologic examination as well as analysis of the patients’ medical
history must be comprehensive. In root-­
filled
teeth, the usually most valuable diagnostic tool,
pulp vitality test, is not available. Therefore, the
risk of a misdiagnosis may be more pronounced.
If the medical history, clinical examination, and/
or radiographic features result in a suspicion of a
nonendodontic lesion, a biopsy and sequential
histopathological analysis are mandatory.
5.3
n Everyday Practical
A
Approach to Diagnosing
Apical Periodontitis in
Root-­Filled Teeth
5.3.1
Diagnostic Strategy
49
false-negative diagnoses, i.e., wants to minimize
the number of sick registered as healthy, the
requirements for a positive diagnosis should be
more including, and a positive diagnosis should be
reported whenever there is a suspicion of disease.
Such a strategy in contrast to above could be characterized as “trap rather than free.” A reduction of
false-positives diagnoses always brings an increase
in the number of false-negative diagnoses and vice
versa. Selection of strategy thus always has a
desired and an undesired effect [33, 51].
It is likely that a more general use of CBCT
would improve the diagnostic accuracy of apical
periodontitis in root-filled teeth. In particular, the
proportion of false-negative diagnoses could be
reduced. But it cannot be ruled out that the risk of
an increased amount of false-positive diagnoses
could also be the result, in particular in the
absence of symptoms and when then the preoperative appearance of the lesion is unknown.
Also, because the dynamics of the healing process over time after root filling is undetermined,
unrestrainedly use of CBCT would bring about
risk of substantial overdiagnosis and as logical
result also overtreatment (for further reading, see
Chap. 6 “Decision Making”). As with any ionizing radiation exposure to patients, the potential
benefits should outweigh the potential risks.
5.3.2
The art and science of diagnosing apical periodontitis in root-filled teeth are hampered by several
difficulties. Misdiagnosis can therefore not be
completely avoided. A deliberate strategy may be
a mean to steer away from unwanted mistakes or
to guide to acceptable and calculated mistakes. If a
clinician, in a given situation, wants to minimize
the number of false-positive diagnoses, i.e., wants
to minimize the number of healthy wrongly diagnosed as being ill, the requirements for a positive
diagnosis should be kept strict, and a positive diagnosis should be reported only when absolutely certain. Adopting such a strategy, the patient or the
tooth “benefits of the doubt.” If, on the other hand,
the clinician wants to minimize the number of
rguments for “Benefit
A
of the Doubt” Strategy
The high frequency of root-filled teeth with periapical bone destructions seems to persist despite
the technical quality of root fillings has improved
over time [52, 53].
Millions of teeth saved to survival and asymptomatic function are present in many countries all
over the world. The risks of a systemic adverse
effect on the health of untreated apical periodontitis may, on the basis of the evidence currently
available, considered small for healthy patients
(see Chap. 4 “Consequences”). Severe acute
infectious condition resulting from apical periodontitis in root-filled teeth is also unusual and
has been estimated to less than 5% over a period
of 25 years [54]. Unfortunately, there is no
T. Kvist and P. Jonasson
50
scientifically established method to distinguish
between different severities of periapical disease.
There is some evidence that there is a connection
between the periapical size and the amount of
involved microorganisms [21]. Many different
microorganisms, in most cases the bacteria but
sometime fungi, have been found in the biofilms
that persist in filled root canals. There are no
accepted scientifically founded clinical methods
to distinguish particularly “dangerous” or “harmless” biofilms from this perspective.
In many cases the root filling quality is poor,
and an apical lesion is apparent to anyone who is
observing the radiograph despite the fact the
patient is free from symptoms. In such cases
there is little or no doubt about the diagnosis; the
tooth should be diagnosed with persistent apical
periodontitis. In other situations, the periapical
radiolucency is big and shows no signs of reduction in size despite adequate root canal treatment.
It may be suspected that the periapical lesion represents a periradicular cyst without any further
healing potential without further treatment [55,
56]. The next steps are to inform the patient and
have a dialogue about how the situation should be
managed. This process is reviewed in Chap. 6.
However, if the root filling quality is reasonable
within acceptable standards, the clinician may
remain ambiguous about the periapical diagnosis.
When uncertain about the diagnosis of apical
periodontitis, it seems likely from the bulk of
available information that most patients will
“benefit from the doubt” when apical periodontitis in an asymptomatic and properly root-filled
tooth is considered. In other words, false-positive
diagnoses should be avoided. This means that the
clinician deliberately should choose to refrain
from diagnosing apical periodontitis in root-filled
teeth when in doubt, rather than taking risk of
diagnosing and hence treating teeth with healed
or healing apical periodontitis.
5.3.3
xceptions from the “Benefit
E
from the Doubt” Strategy
A careful medical history is important for all
patients under dental care. There are several med-
ical conditions and medications that cause a deterioration of the immune system, by the lack of
white blood cells or the inability of a patient to
produce antibodies.
In such situations, maybe that “trap rather
than free” attitude by the clinician may be the
best diagnostic strategy. However, it is unclear to
what extent medically comprised patients benefit
from diagnoses and in particular treatment of
asymptomatic apical periodontitis in a situation
of ongoing medications or disease that impede
normal function of the immune defense system.
5.3.4
ome Common Situations
S
and Guidelines for
Determining Diagnosis
In the following we will give some typical examples where there may be an uncertainty regarding
potential residual apical periodontitis in a root-­
filled tooth. We are also suggesting a concrete
policy reaching a diagnosis in each one of the
situations.
5.3.4.1 P
ain from Root-Filled Tooth
But No Sign of Apical
Periodontitis on Intraoral
Radiographs
The patient may experience soreness—pain or
discomfort from a root-filled tooth. However,
intraoral radiographs from one or two angulations show no apical radiolucency. The root filling exhibits good technical quality as can be
judged from the radiographs.
Action: Suggest a CBCT scan.
If this shows that an apical radiolucency is
present, there is indication for retreatment or in
some cases extraction.
If no radiolucency, or other pathology, can be
observed, one can suspect that the endodontic treatment caused a damage to sensory nerves involved.
Or that pain is projected from a TMD disorder.
There is no diagnosis of apical periodontitis and
consequently no indication for retreatment or
extraction. Instead extend the examination and
consider other diagnoses that may mimic the symptoms of apical periodontitis in a root-filled tooth.
5 Diagnosis
5.3.4.2 Asymptomatic Tooth
But a Widened Periapical
Contour
Another common situation is that the patient is
asymptomatic; the root filling exhibits good technical quality. But, there is a widening of the periapical contour present.
Action: An expanded periodontal contour
should not be considered pathological. The diagnosis shows great observer variations. Great
uncertainty is present. The patient and tooth benefit from the doubt if no other findings suggestive
of apical periodontitis are present.
5.3.4.3 Asymptomatic Tooth
But Clinician Is Uncertain
About a Possible Lesion
A similar common situation is that the patient is
asymptomatic. The root canal exhibits good
technical quality. However, the clinician is in
­
doubt whether a periapical lesion is present or
not.
Action: Consultation with a colleague on the
radiograph. If the uncertainty persists, consult a
radiologist who must decide.
5.3.4.4 A
symptomatic Tooth: A Lesion
Is Present But Short Time
Since Root Filling
In this scenario the patient is asymptomatic.
However, there is an apical radiolucency evident
in the intraoral radiograph. Root canal shows
good technical quality. Relatively short time
passed since the root canal treatment and root filling were performed (1–4 years).
Action: Good to fairly good healing potential
remains. The closer to the point of root filling, the
larger remaining of healing chances. Wait for
periapical healing at least 4 years.
5.3.4.5 A
symptomatic Tooth: A Lesion
Is Present Showing Reduced
Size
Our last example is equally frequent. The patient
is asymptomatic. Root filling shows good technical quality. More than 4 years have passed since
root filling was performed. There is an apical
radiolucency. However, compared with previous
51
X-ray, it shows the radiolucency clearly and continuously reduced in size.
Action: Further healing potential may remain.
Wait further healing and check again.
5.3.5
Patient Information
and the Adoption of Measures
When the diagnosis of apical periodontitis is
made, it is the dentist’s statutory obligation to
inform about the diagnosis and demonstrate the
potential of therapy. The dentist should also give
suggestions on the treatment that he/she deems
most appropriate. In addition, the dentist must
inform if the treatment is requiring a referral to a
specialist or not. It is the patient who must take
the final decision to treat or not. This process will
be further covered in Chap. 6.
Take-Home Lessons
• When pain and/or swelling or a sinus
tract from a root-filled tooth is present
and at the same time an apical radiolucency can be observed on an intraoral
radiograph, the diagnosis of apical periodontitis is evident.
• When pain from a root-filled tooth registered without concomitant other clinical or radiographic signs of disease, a
handful of other diagnoses should be
considered, among them referred pain
from TMD and neuropathic pain
disorders.
• When clear radiographic signs of apical
periodontitis are present, the diagnosis
is usually evident because of poor-­
quality root filling giving obvious space
for microbial biofilm to persist.
• When radiographic signs of apical periodontitis are uncertain, the diagnosis is
surrounded by major uncertainties,
especially if root filling quality is good.
In such situations, we argue most
patients will “benefit from doubt”—
diagnostic strategy.
T. Kvist and P. Jonasson
52
Benchmark Papers
• Brynolf I. Histological and roentgenological study of periapical region of
human upper incisors. Odontologisk
Revy. 1967;18(Suppl. 11). In this classical thesis, the author studied the periapical regions of root-filled teeth with
histological as well as radiographic
examinations. The studies provided data
for the PAI score.
• Reit C, Hollender L. Radiographic evaluation of endodontic therapy and the
influence of observer variation. Scand J
Dent Res. 1983;91:205–12. The authors
clearly and elegantly demonstrated the
intra- and interobserver variation problems involved in the diagnosis of periapical lesions in intraoral radiographs.
• Reit C, Gröndahl HG. Application of
statistical decision theory to radiographic diagnosis of endodontically
treated teeth. Scand J Dent Res.
1983;91(3):213–8. The study explains
why variations between the observers
could be explained by their adoption of
different criteria of periapical disease
resulting in different positions on the
ROC curve. It also explains why the best
opportunities for revealing relative differences in disease prevalences are created when the examiner defines a strict
criterion for disease and reported a
positive finding only when absolutely
certain.
• Strindberg LZ. The dependence of the
results of pulp therapy on certain factors. Acta Odontol Scand 1956;14(Suppl.
21). Classical study on outcome of root
canal treatment clearly demonstrating
that the number of healed cases will
increase in the long term, also after
such a long period as 4 years.
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34. Rosen E, Taschieri S, Del Fabbro M, Beitlitum
I, Tsesis I. The diagnostic efficacy of cone-beam
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6
Decision Making
Thomas Kvist
I used to be indecisive but now I am not quite sure.
—Tommy Cooper (1921–1984). Welsh comedian and magician.
Abstract
In this chapter the complexity of any clinical decision making process is
briefly sketched out.
Descriptive as well as prescriptive projects regarding endodontic
retreatment decision making are reviewed. The inherent ethical aspects of
any prescriptive system are emphasized.
But this chapter also gives simple guidelines for the clinician’s everyday decision making regarding persistent apical periodontitis.
6.1
Introduction
Clinical decision making is a term frequently
used to describe the fundamental role of any physician or dentist. It concerns the process where
data are gathered, interpreted and evaluated in
order to select a choice of action. Having an
understanding of the complexity and the different
approaches to the task will allow for development
and improvement in daily care of our patients.
Clinical decision making is the process by
which we determine what the patient needs and
when he or she needs it. While not arbitrary, this
exercise can be quite subjective. Each clinician
compiles their own data and then constructs an
argument for a particular disease state based on
their interpretation of the “facts”. The strength of
their case will depend on the way in which they
gather and assemble information. There may then
be no single, right way of applying therapeutic
strategies to a particular case. Dentistry is not an art
like painting. But, neither is it a science like physics. It’s an applied science. Since each patient is a
unique being, it can be very tricky to decide how to
apply the science and evidence to each individual
case and situation. In this chapter I will discuss
some various aspects on clinical decision making
for root-filled teeth with apical periodontitis.
6.2
T. Kvist, DDS, PhD
Department of Endodontology, Institute of
Odontology, The Sahlgrenska Academy,
University of Gothenburg, Göteborg, Sweden
e-mail: kvist@odontologi.gu.se
© Springer International Publishing AG 2018
T. Kvist (ed.), Apical Periodontitis in Root-Filled Teeth,
https://doi.org/10.1007/978-3-319-57250-5_6
Available Options
When a diagnosis of apical periodontitis in a rootfilled tooth is present, theoretically four options
are available: (1) no treatment, (2) monitoring
55
T. Kvist
56
No replacement
Extraction
Fixed prosthesis
Implant
Therapy
Surgical retreatment
Non surgical retreatment
Monitoring
Fig. 6.1 A decision tree
logically displaying
alternative actions in the
management of
root-filled teeth with
apical periodontitis
No therapy
(wait and see), (3) extraction and (4) retreatment.
If retreatment is selected, the decision maker also
has to make a choice between a (a) surgical and
(b) nonsurgical treatment (Fig. 6.1).
6.3
ariation in Endodontic
V
Retreatment Decision
Making
In a benchmark, experimental study, Reit and
Gröndahl [1] confronted 35 dental officers from
the Public Dental Health Organization in Sweden
with 33 endodontically treated teeth with radiographic signs of persistent apical periodontitis.
In no case was the same option suggested unanimously by all observers. The number of teeth
selected for therapy (surgical or nonsurgical
retreatment or extraction) had an inter examiner
range of 7–26 teeth. Petersson et al. [2] scrutinized 1094 treatment plans including radiographs submitted to the Swedish dental insurance
system by general practitioners. In 874 rootfilled teeth, a periapical radiolucency was diagnosed by the authors. According to the treatment
No monitoring
plan, extraction, periapical surgery and conventional retreatment were suggested for 23%, 3%
and 20%, respectively. However, for the remaining 472 cases (54%), no intervention was prescribed. In another study, Petersson et al. [3]
re-examined a sample of 351 individuals from a
randomly selected cohort of 1302 persons radiographically examined 11 years earlier. It was
found that 33 (40%) of the endodontically treated
teeth with periapical bone lesions at first examination had been retreated or extracted, while the
remaining 49 teeth had received no radiographically detectable treatment. This quandary continues to attract attention from various aspects
among researchers, and the overall conclusion is
that there is no consensus [4, 5]. In particular, the
constantly repeated observation that the mere
diagnosis of apical periodontitis does not consistently lead to clinical action has attracted special
attention [6].
The implementation of dental implants to
replace a compromised tooth has made the
issue even more marked and controversial
which has been highlighted in numerous publications in recent years [7, 8].
6
Decision Making
6.4
ariation in Medical
V
and Dental Care
Variation in health-care procedures was recognized early, at the beginning of the twentieth century. In a classical study [9] of 1000 11-year-old
schoolchildren in New York City, it was found
that 650 children had undergone tonsillectomy.
The remaining 350 children were sent to a group
of physicians. One hundred and fifty-eight children were selected for tonsillectomy. Those
rejected (192) were sent to another group of physicians, and 88 of them were then suggested for
tonsillectomy. After that, the remaining children
were examined by a third group of physicians,
and then only 65 children remained for whom
tonsillectomy had not been suggested. At that
point the study was interrupted owing to a shortage of physicians to consult.
Variation in care is a real challenge to many
areas within medicine and health care [10–13] as
well as dentistry [14–16].
Already in 1984 Eddy [10] condensed the
worrisome situation:
Uncertainty creeps into medical practice through
every pore. Whether a physician is defining a disease, making a diagnosis, selecting a procedure,
observing outcomes, assessing probabilities,
assigning preferences, or putting it all together,
he is walking on a very slippery terrain. It is difficult for nonphysicians, and for many physicians, to appreciate how complex these tasks are,
how poorly we understand them, and how easy it
is for honest people to come to different
conclusions.
Owing to its intricacy, clinical decision making
has attracted interdisciplinary attention. In
addition to interest from health professionals,
philosophers, psychologists and economists
­
have also contributed [17]. Two main spheres of
research and thinking can be identified: descriptive and prescriptive. Descriptive projects aim
at mapping out and explaining how clinicians
reason and make decisions. Prescriptive, or
normative, projects, on the other hand, are
involved with how decisions should or ought to
be made.
57
6.5
linical Decision Making:
C
Descriptive Projects
In studies of clinical reasoning, several models
have been suggested and used [17]. Some investigators have focused on the artistic, or intuitive,
aspects of clinical practice [12, 18].
In the tradition of “judgement analysis” [19],
researchers have tried to reveal the pieces of
information or “cues”, used at conscious or
unconscious levels, that influence a person’s
decision making policy. This approach has been
applied in several domains [20] including judgements of third molar removal [21]. In a series of
investigations, Kahneman and Tversky [22]
explored a proposition that people most often
rely on a small number of heuristic principles to
make decisions. Their gathered important insights
into human thinking and decision making were
admirably summarized the other year by Nobel
laureate Kahneman [23].
6.5.1
Descriptive Projects
on Endodontic Retreatment
Decision Making
Attempts have been made to explain the observed
variation in the management of periapical lesions
in endodontically treated teeth. Since several
studies have demonstrated large interindividual
variation in radiographic interpretation of the
periapical area [24], it has been hypothesized that
variation in retreatment decisions might be
regarded as a function of diagnostic variation.
However, nor studies among general practitioners [25] or specialists [5, 7] have given support
to this idea. Rawski et al. [26] applied the above-­
mentioned “judgement analysis” model. The
complexity and multiplicity of factors present
in different studies of the phenomenon have
­rendered it difficult to present a coherent model
to explain the observed variation. But the diagnostic difficulties, timing and the question of
what should be regarded as healthy and diseased,
as well as several other factors, partly explain the
T. Kvist
58
large variation among dentists regarding retreatment decision making [6].
6.5.1.1 The Praxis Concept
The Strindberg [27] criterion of classifying the
results of endodontic treatment into “success” and
“failure” represents an “ideal” concept of disease.
According to Juul Jensen [28], such criterion is
demarcated and made explicit by a formal definition. However, by no way are all our concepts
defined in such a precise way. Still these concepts
exist. They exist in the sense that we use them.
Such concepts are referred to as “praxis concepts”
by Juul Jensen [28]. In search of a theory that
could, at least partly, explain the variation in retreatment decision making, a “praxis concept” of periapical health and disease following root canal
treatment was generated and tested in a series of
written case simulation design studies [29–31].
In this “praxis concept”, it was proposed that
dentists consider periapical health and disease, not
as either/or situations, but as states on a continuous
scale. On this scale a major lesion represents a
more serious condition than a smaller one. Variation
between decision makers could then be regarded as
the result of the individuals’ selection of differing
cut-off points on the scale for prescribing retreatment. The investigations gave support to the view
that a periapical health continuum is the basis of a
praxis concept. Factors unrelated to the disease per
se (costs, technical quality of root filling, access
problems) also seemed to contribute to the final
placement of the cut-off point. These studies also
emphasized the subjective influence of personal
values on the selection of retreatment criterion.
Similar patterns among clinicians’ root canal
retreatment strategies were also found among dental students in Saudi Arabia [32] and general practitioners and specialists in Australia [7].
6.5.2
Personal Values
According to the praxis concept, a dentist’s values
influence the recommendation of endodontic
retreatment. The concept of value is multidimensional, but it seems sound to assume that there is a
close connection between an individual’s values
and his or her value judgements. It has been suggested that one may apprehend values in acts of preferring [33, 34]. This means that when faced with a
choice, the values of an individual are reflected in
his preference behaviour. For example, the value of
health is given in preferring it to disease.
The subjective values of endodontic health
states in root-filled teeth were investigated among
dental students [35] and specialists in endodontics [30].
In these studies, students and endodontists
were asked to judge a health state of a root-filled
incisor with no signs of periapical pathology, and
one health state where a periapical radiolucency
was diagnosed. The two health states were placed
on a utility scale extending from “perfect pulpal
and periapical health” (value = 1) to “loss of the
tooth” (value = 0). Large interindividual variations in value judgements were found for both
situations. Nevertheless, most raters assigned
higher values to a situation were no signs of
pathology were present compared to a situation
with a periapical lesion present. Nevertheless,
these studies failed to show any significant correlation between the retreatment prescriptions and
the elicited values. However, the assessment of
value judgements is a complex task, and the methods of eliciting them and the reliability and validity of obtained values may be questioned [36].
6.5.3
he Benefit of Endodontic
T
Retreatment
According to von Wright [37], something is beneficial to a being when the doing or having or happening of this thing affects the good of that being
favourably. He suggests that when the being in
question is a human being, the phrase “the good
of a being” can be understood in two different
ways: in terms of welfare and in terms of health.
This means that a treatment procedure is beneficial to a patient if it is in some way conducive to
his welfare (or well-being), or if it is conducive to
his (bodily or mental) health or both [38].
From a dental health point of view, a patient
will benefit from endodontic retreatment if he or
she moves from a health state with a periapical
6
Decision Making
59
Subjective benefit of retreatment
Patient B
0.75
Subjective benefit of retreatment
Patient A
0.30
Utility value
1.0
Tooth with
healthy pulp.
0
No tooth
Assessment patient A
0.35
Root filled tooth
with apical periodontitis.
0.65
Root filled tooth
without apical periodontitis.
0.90
Root filled tooth
without apical periodontitis.
0.15
Root filled tooth
with apical periodontitis.
Assessment patient B
Fig. 6.2 An individual may benefit from endodontic
retreatment by moving from a state with an asymptomatic
lesion to a state where the lesion has healed. The numeri-
cal difference in assigned utility values can be defined as
the “subjective benefit of retreatment”
inflammation to a post-retreatment situation where
the lesion has healed. If the health states are placed
on a utility scale, the subjective benefit of endodontic retreatment can be defined as the distance
between the two states (Fig. 6.2). Presumably, endodontic retreatment will contribute to a person’s
well-being and health in proportion to the individual length of the distance between the health states.
In an investigation involving 16 endodontists, it
was found that the assessment of “retreatment benefit” was subjected to substantial interindividual
variation [30]. This was due above all to the experts’
deviations in their judgement of the value of the
persistent periapical lesion. The findings clearly
demonstrated that the “benefit” of endodontic
retreatment varies among individuals and highlight
the necessity of “consumer” influence in clinical
decision making. From a subjective point of view,
some patients will benefit much more from endodontic retreatment than others. It also suggests
that the value-laden terms “success” and “failure”
are meaningful only in the clinical patient-dentist
context. Both doctors’ and patients’ values will
influence the decision making process.
Today patient autonomy is widely regarded as
a primary ethical principle, emphasizing the
importance of paying attention to the values and
preferences of the individual patient in any prescriptive theories of clinical decision making.
6.6
linical Decision Making:
C
Prescriptive Projects
Prescriptive projects in clinical decision making
are fundamentally an issue of ethics. Prescriptive
ethics, or normative ethics (syn), is the branch of
philosophical ethics that investigates the set of
questions that arise when considering how one
ought to act, morally speaking. Prescriptive ethics is consequently distinct from descriptive ethics, as the latter is an empirical investigation of
people’s moral beliefs or values. To put it another
way, descriptive ethics would be concerned with
determining what proportion of dentists believe
that endodontic retreatment should be performed,
while prescriptive ethics is concerned with
whether it is correct or not to hold such a belief.
T. Kvist
60
6.6.1
Ethics: What It Is
Ethics deals with that which is good or bad, what
should or should not be done and what characteristics make us better or worse as individual
human beings. The central question in normative
ethics concerns the right procedure; its role is to
clarify how ethical questions should be managed,
i.e. what should be done in a certain situation and
what should be avoided [39]. A course of action
can be wrong on ethical grounds in two different
ways. Either there is something offensive in the
course of action itself that makes it unacceptable,
regardless of the expected consequences of the
action, e.g. because those concerned are not
treated with respect and dignity, or that it violates
basic human rights. Or the expected negative
consequences exceed the expected benefit, and
thus the action is disallowed. If there is profound
objection in principle against the course of action,
then there is no cause to reason further and weigh
the positive and negative consequences. In other
cases, these consequences should be considered.
Ethics in health care is concerned primarily
with how the individual patient should be treated,
i.e. what is beneficial and what is harmful to the
patient, respectively. Several patient-related
interests become relevant. Normally and particularly issues regarding health and well-being are
central to dental ethics. But also, questions
regarding and autonomy and integrity are highly
relevant. Ethics in dentistry, however, covers
more than the individual patient. Effectiveness,
priority and fairness are also relevant aspects of
ethics, as are questions about how to weigh up
the interests of the patient against research interests (see Chapter “Consequences”).
The following four principles, which are well
established in biomedical ethics, are often presented as a basis for ethics in health and medical
(and dental) care [40]:
1. The do-good principle means that one should
try to help the patient by satisfying his or her
(medical and basic human) needs.
2. The do no harm principle means that one
should avoid harming the patient. One should,
for example, avoid taking unjustifiable risks.
3. The autonomy principle means that one should
respect the patient’s right to self-­determination,
which implies that one must keep patients
informed and guarantee them the right to
decline the treatment being offered.
4. The principle of fairness or justice means that
patients with similar needs should be treated
similarly. That is, it is the patient’s treatment
need which should determine the course of
action, not—for example—the patient’s cultural background, gender, financial or social
standing.
The principles in themselves do not suggest an
order of priority in cases of conflict. One can easily imagine situations where the treatment which
is most likely to improve the patient’s dental
health is at the same time associated with greater
risk than other treatment options. In such a case,
which principle should be applied, the “do-good”
or the “do no harm” principle? A similar conflict
can arise between the “do-good” principle and
the autonomy principle, in cases where the
patient does not want to accept the treatment,
which the dentist recommends. However, the
four principles are not intended as a total ethics
package for solving ethical problems. The purpose is more to remind us of core ethical principles, which should be taken into account and
guide us in clinical decision making.
6.6.2
The “Strindberg System”
In endodontics, the system of dichotomizing the
outcome of root canal treatment into “success”
and “failure” launched by Strindberg [27] has
achieved paradigmatic status as a normative
guide to clinical action. According to Strindberg
[27], the only satisfactory post-treatment situation, after a predetermined healing period, combines a symptom-free patient with a normal
periradicular situation. Only cases fulfilling these
criteria were classified as “successes”, and all
others as “failures”.
Consequently, when a new or persistent periapical lesion is diagnosed in an endodontically
treated tooth, the Strindberg system prescribes
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Decision Making
retreatment (or extraction). The Strindberg system is exclusively based on biology and can be
perceived as dogmatic and inflexible. Although
generally accepted in academic institutions,
available studies and experience indicate a weak
position among general practitioners [3, 7, 31,
41, 42].
6.6.3
Expected Utility Theory
One of the most highly developed normative
decision making models is the “expected utility
theory” (EUT). For reviews see Hargreaves Heap
et al. [34] and Bacharach and Hurley [43]. The
philosophical foundation of the model is to be
found in classical utilitarianism [44, 45], while
its mathematical origins are even older [46]. The
advent of modern EUT is associated with the
influential work of von Neumann and
Morgenstern [33] which made some of the psychological assumptions of utilitarianism redundant. During the last 70 years, EUT has prospered
mainly in economics and the social sciences. The
theory was introduced to medicine by Ledley and
Lusted [47]. “Clinical decision analysis” has
received much attention in medicine and also in
dentistry [48].
EUT prescribes that the problem should be
structured as a “decision tree”, which (i) logically
displays available actions and their possible consequences. Then (ii) the listed outcomes are
assessed regarding probabilities and subjective
values (“utility”). After this (iii) the weighed sum
(expected utility) of each strategy is computed,
and (iv) the action with the highest sum is
chosen.
Reit and Gröndahl [1] approached the management of periapical lesions in endodontically
treated teeth from a decision analytic point of
view. Even if EUT may be questioned as a normative theory, it does point out two essential
components of a basis for making clinical decisions: empirical facts and subjective values. Later
these authors drew attention to the fact that the
critical information needed for the analysis were
either not available (utility values) or very uncertain (outcome probabilities) [49].
61
6.6.4
Evidence-Based Decision
Making
In more recent years, the development of the concept of evidence-based medicine/evidence-based
dentistry has come to supplement and to some
extent replace the formal clinical decision analysis [50].
Evidence-based medicine is “the conscientious, explicit and judicious use of current best
evidence in making decisions about the care of
individual patients”. This well-known definition
emanates from the highly cited report published
by David L. Sackett and collaborators in the 1996
British Medical Journal [51].
While evidence-based medicine/evidence-­
based dentistry basically is concerned with the
efficiency of the clinical procedures that we apply
to treat our patients, in order to achieve the best
possible outcome for each patient based on the
best knowledge and available resources the concept has not always been generally agreed upon
and the concept has nowadays, in some instances,
been given a wider meaning and has become
something of a buzzword. However, during
recent years hundreds of books and thousands of
articles have been published using this conception. In addition, websites and various other
channels of information issued by researchers,
clinicians and organizations have been released
on this new concept in the clinical practice of
health care including dentistry.
Bergenholtz and Kvist [52] reviewed the
essence of the concepts and its impact on endodontics. Like Reit and Gröndahl [49], 30 years earlier,
the authors reported that evidence-based data on
various outcomes associated with apical periodontitis in root-filled teeth is largely lacking, and also
patients’ preferences are difficult to estimate.
6.6.5
Autonomy and Information
The principle of autonomy is highly relevant to
diagnosis and treatment of apical periodontitis in
root-filled teeth. What should patients decide? What
information should the dentist provide and should
any information be withheld from the patient?
62
The mouth is an intimate part of the body. It is
therefore reasonable to assume that it is important for people to make their own decisions about
their teeth, not least with respect to any treatment. In order to make informed decisions about
their own dental care, patients require relevant
information. In circumstances where there is a
lack of knowledge about the expected benefits of
different treatment options, it is difficult to provide information, which offers the patient a basis
for decision making. It is also difficult to analyse
the value of different options from a general point
of view. It is therefore important from both an
individual patient and a community perspective
that research is conducted to improve our knowledge of the effects of the various options for root-­
filled teeth with apical periodontitis. In the future,
this will allow the clinician to offer better information to patients and thus for the patient to
assess various action alternatives.
As indicated by the many epidemiological
studies and the experiments on endodontic
retreatment decision making among clinicians,
asymptomatic apical periodontitis associated
with root-filled teeth is often not considered as an
indication for retreatment, and hence these teeth
are left without treatment. Is this wrong? Is the
dentist under an obligation to inform the patient
of the situation? Furthermore, a not inconsiderable portion of the cases is a consequence from
previously improper root canal treatments.
Should the dentist inform the patient about previously inadequate treatment? From the perspective of autonomy, the answer to these questions
seems obvious. Anyone wanting such information about their dental status should have the
right to this if the information is found during an
examination at a dental appointment.
A difficulty is that some patients do not wish to
receive such information, i.e. they prefer not to
know unless the information has a clear and direct
bearing on their health and/or well-being.
Consequently, the dentist needs to ascertain
beforehand what attitude the patient has to such
information, in order to show due consideration to
both patients who want to be fully informed and
those who do not. To ask the patient whether he
wishes to receive such information is reasonably
T. Kvist
no adequate strategy because the patient may
draw the conclusion that the dentist now has some
information or would otherwise not have asked.
It may be challenging to have to inform a
patient that previous treatment has not been successful, as there is a risk of singling out oneself or
a colleague in a negative way. This is sometimes
unavoidable if the patient is to receive relevant
information. In the case of diagnosing someone
else’s “failure”, it is important to combine objectivity in presenting the information with a
respectful attitude, since it is usually impossible
to fully appreciate under what circumstances the
treatment was accomplished.
6.6.5.1 Monitors and Blunters
Kristina is a 62-year-old teacher, and I have just
told her that the X-ray of her upper left first molar
does exhibit a periapical radiolucency and an
inadequate root filling. The root canal treatment
was done 6 years ago. I tell her that this indicates
a persisting root canal infection and that it might
become symptomatic sooner or later. I suggest a
CBCT examination for better imaging, verifying
the diagnosis and support for decision making. I
am telling her that a minor surgery might be
needed to solve the problem. Then I tell her that I
will contact her again when I have looked at the
CBCT results and suggest a treatment plan. “Will
it be painful to do a surgery?”, she asks slightly
surprised. “No it is a standard procedure done
with local anaesthesia at our clinic”, I answer.
“Do you have any further questions”, I ask. “No,
I trust you to tell me what I need to know”, she
answers before rising from chair and leaving.
In the same week, I see John, a 50-year-old
shop owner, for a check-up of a root canal treatment of a lower first molar I finished 1 year ago.
The X-ray shows that the periapical radiolucency
is unchanged in size. I am telling him that no
signs of healing are yet visible but that is too
early to diagnose it as a “failure”. I suggest further follow-up with a new X-ray for another year.
Unlike Kristina, John has a lot of questions.
“How come that healing has not occurred yet?
Are there bacteria left in the tooth than? Isn’t
dangerous? Perhaps you should have taken my
tooth out already from the beginning? Will I have
6
Decision Making
pain now? What will you suggest if you don’t see
healing at next check-up either? Will I have to go
through any further treatments?” he asks. “I
have many friends who also had root canal treatments and they never said that it took so long to
heal. I'll probably ask them. Then I will go on the
Internet and search as many sites as I can about
this. My feeling is that something is wrong and I
need more information”.
It is striking how two patients facing similar
situations took two very different approaches to
gathering and processing information. Miller
[53] has categorized these two approaches to
information seeking under threat as “blunters”
and “monitors”. The blunter—Kristina—wants
just the basics, while the monitor—John—craves
more information. High monitors and low blunters chose to seek out information about its nature
and onset, whereas low monitors and high blunters chose to distract themselves. Each style has
its strengths and weaknesses. But, under unfavourable conditions, both styles risk becoming
more flawed and hamper a good patient-dentist
relation.
My own clinical experience is that people react
very differently to the information about signs of
persistent apical periodontitis. Health information
is not neutral, especially when you’re the one
affected by a condition. If you, who are reading
this, have your own experience of root canal treatment, you have probably experienced how different it is when you are reading about it as a
professional, as opposed to when you had the procedures executed on your own tooth.
“We don’t see things as they are, we see them
as we are” is a quotation with several suggested
origins that captures the essence of our argument.
Most people fall somewhere in between the
two extremes of blunter and monitor. Most of our
patients want to know to appraise and understand
the options without going into too many details,
but some just want to say, “Just tell me what to
do. That’s fine”.
The notion about different psychological dispositions towards information and the variation
in attitudes to apical periodontitis result in considerable challenge to the dentist and the decision
making process.
63
6.6.6
Informed Consent
The requirement that a medical or dental action
should be preceded by informed consent is
deemed very important in medical ethics [40].
It is important to appreciate that it is not
enough that a patient has received written or oral
information and then consented. The informed
consent has two components: information and
consent. The patient must have accepted and
understood the information and not only received
it. All the relevant aspects of the situation should
be informed about in an appropriate way. The
dentist should not only convey information but
also need to ensure that the information is correctly recognized. In order to take a position in an
independent way in a choice situation, the patient
must also be informed of the alternatives and be
free to choose, i.e. not be subjected to compulsion, or in such a position of dependence that the
free informed choice becomes an illusion.
In a dental surgery, there are many circumstances that can hamper patients’ ability to
acquire and rationally process the information
given. The environment and situation may seem
frightening and lead to both anxiety and worry,
which can confuse a generally well-functioning
sense and judgement. To ascertain that the patient
comprehends the information may thus be difficult. It is important that the dentist is attentive to
both verbal and non-verbal expressions.
At the same time, one must have realistic
expectations of the patient’s ability to understand and evaluate the options. Certainly, this
can vary greatly between individuals. For
patients who want to have full control over the
decision, doctors should make sure to make this
possible, but one must also allow the patient to
hand over a part of decision making if he or she
so wishes. A professional reception of each individual patient at the dentist’s office creates a
seedbed for a high confidence that the patient
can feel safe with both for the decision making
and forthcoming treatments.
In everyday clinical practice, an oral consent
is normal and also appears naturally. A written
agreement could be seen as well formal and
might also get the patient to wonder what kind of
64
exceptional measures that require such formalities. However, in many countries and in research
contexts, it is quite common or even compulsory
with written informed consent documentation.
6.6.6.1 Information About Treatment
Patients in the dental care can hardly be expected
to have knowledge and understanding of all the
factors that can and should be taken into consideration before a clinical decision about an endodontic retreatment. The patient has the right to know
what the different treatment alternatives entail,
how risky and painful they are and what impact it
is likely to bring with them to undergo treatment
and to refrain from it. This implies a corresponding requirement for dental staff to ensure that this
information is provided and that it is done in a
way that the patient can actually understand. In
practice, there is of course a limit on how detailed
information can be allowed to become. If patients
ask many questions about the equipment and
methods, this can be an expression of concern, or
at worst, distrust, rather than a genuine desire for
more detailed information. As important as providing answers to all the questions, then is to try
to establish or re-establish trust. The patient
should be able to rely on dentists’ knowledge
based on science and proven experience and that
they follow both the technological and scientific
developments in the field. They should also be
confident that the dentist has the best for the
patient as their primary goal.
6.6.6.2 Information About Risks
For a patient to be adequately informed, something must be said about the risks associated with
the suggested treatment but also to refrain from
treating. In our particular case, this is complicated
significantly due to the fact that evidence is lacking about how the untreated apical periodontitis
affects individuals both locally and systemically.
There are two basic aspects of risk: some kind
of negative consequence and the probability that
it will occur. The negative consequence or injury
may be more or less severe. The most serious
negative consequences, death or lifelong pain or
suffering, are very unlikely as a consequence of
either leaving or treating apical periodontitis in a
root-­filled tooth. Other risks are more frequent
T. Kvist
but at the same time the consequences are not
very severe and of transient nature.
If only it had been advantages to inform, there
would have been no reason to hesitate about.
What complicates the matter is that information
in itself can cause injury. Risk information may
cause anxiety, and it can make patients refrain
from treatments because of unrest despite the
risks otherwise would be reasonable to accept.
This is why there may be reason to wonder, for
example, whether to communicate a very small
likelihood of great harm. Primarily because it is a
concern from dentist’s point of view to promote
patient’s oral health, but also from the autonomy
perspective, it is sometimes questionable whether
such information should be given. The fear of an
unlikely but serious injury may counteract the
ability of the patient to rationally reflect on the
options and come to an autonomous decision.
Exactly how much information and into what
level of detail that should be made are debatable.
Some patients prefer not to know the risks unless it
is clearly relevant. How much and what to inform
varies with the situation and who is the patient.
6.6.6.3 Information on Costs
When deciding about a tooth in possible need of
endodontic retreatment the economic aspect of
the treatment is, if not decisive, then at least a
very important factor. It is important that information about the costs and possible reimbursement by insurance are correct and that it does not
change. Also, costs for alternative strategies, i.e.
extracting the tooth with or without replacement,
should be clearly accounted for.
6.6.6.4 Information and Manipulation
When the patient is informed of the facts regarding diagnoses, treatment options, risks and costs,
he or she must be allowed to choose what she
wants to do in the given situation. The individual
has a right not to be forced or manipulated to
undergo dental treatments. However, it is difficult
to imagine that the dentist can completely avoid
the influence. The positive approach to good
oral and dental health and in this particular case,
the importance of restoring periapical health is
likely to affect the patient to some degree. One
might think that it is also reasonable, since good
6
Decision Making
p­ eriapical health, in the same way as teeth without
cavities and with good periodontal health, appears
to be the intrinsic and undisputable objectives of
dental care. Here, there is an important balance to
go so that patient autonomy is not compromised.
6.6.6.5 Authorized Informed Consent
Many patients lack all or part of the capacity for
autonomous decision making. It may involve
children, mentally ill, mentally retarded or
demented individuals. It is important to remember that these patients have the right to be treated
with care and respect. A fruitful way to address
the challenge of information and consent for
these patients is to allow them to exercise their
autonomy as best they can and otherwise let them
express their willingness or unwillingness to
cooperate. In the absence of the ability to understand, to take a stand and to make decisions, can
the informed consent be authorized to a close
relative or another person close to the patient?
6.7
Guide to Everyday
A
Decision Making of Root-­
Filled Teeth with Apical
Periodontitis
6.7.1
Philosophical Justification
The British philosopher RM Hare [54] makes a
distinction between two levels of moral reasoning
and hence decision making: the intuitive and the
critical. The intuitive level is the level at which
most of us make decisions about moral matters
most of the time. We rely on relatively simple,
specific and intuitive principles to guide us in routine circumstances. However, it is also possible to
reflect on those principles, to step back and to
critically assess them. This is the level of critical
thinking. At this level, empirical facts and value
judgements are considered rationally in order to
establish and select principles which can be followed in everyday life at the intuitive level.
Social development has led to the conclusion
that we are currently seeing the patient’s right to
autonomous decision making as an integral part
of both dental care and other health services.
Consequently, a paternalistic approach to clini-
65
cal decision making must be ruled out. The
Strindberg dichotomy of post-treatment situation
into success and failure exclusively founded on
biology is neutral to different agents and clinical
situations [27]. Therefore, it cannot alone be used
on an “intuitive level” rule for clinical decisions
about endodontic retreatment.
In medical and dental decision making matters, it is often difficult to imagine all outcomes
and to assess their probabilities and elicit trustworthy value judgments. This holds true also for
apical periodontitis in root-filled teeth. However,
even if it was humanly possible to compute the
probabilities and utilities of all possible outcomes, it would often be absurd, time-consuming
and counterproductive. From a critical level
­perspective, calculations should be made on the
intuitive level only if they bring about the best
consequences. If not, other decision strategies
should be used. Better overall results may come
from acting in accordance with principles or
rules. In many clinical situations, we can safely
act on well-established precepts, and in others we
ought to stick to prima facie rules. In order to
achieve the best results for everyone involved, the
clinician, at the intuitive level, should probably
normally follow a few simple principles rather
than engaging in difficult and about outcomes
and preferences.
A prima facie rule is an obligation which is
initially binding until a stronger and overriding
duty emerges. The expression prima facie means
“first appearance”, and in philosophy it is associated with the reasoning initiated by Ross [55]. He
argued that we intuitively perceive a small set of
foundational prima facie duties which are the
basis of all judgements when moral issues are
involved. Ross lists the following seven prima
facie principles: promise keeping, reparation for
harm done, gratitude, justice, beneficence, self-­
improvement and non-maleficence. In the influential work on biomedical ethics of Beauchamp
and Childress [40], the prima facie idea was further processed and the principles reduced to the
previously mentioned four: respect for autonomy,
beneficence, non-maleficence and justice.
According to Hare [54] the four principles
could be justified by the golden rule: “Therefore
all things whatsoever ye would that men should
T. Kvist
66
do to you, do ye even so to them: for this is the
law and the prophets” (St Matthew 7:12).
The following principles about decision making regarded apical periodontitis in root-filled
teeth are suggested and formulated from a dentist’s perspective [6].
meaning of the situation will differ among patients.
Only the patient is the expert on how he or she
feels about keeping a tooth with or without retreatment or perhaps extracting it, which symptoms are
tolerable, which risks are worth taking and what
costs are acceptable. These, subjective and personal values, must be allowed to influence the
1. First principle: Apical periodontitis in a root-­ decision making process.
filled tooth that is not expected to heal should
be retreated.
(b) Retreatment risks
Motivation: It is assumed that the best overall consequences are obtained if dentists’ primary suggestions to patients, at the intuitive level, are to perform
endodontic retreatment when a persisting apical periodontitis is diagnosed. The persistent lesion is an
expression of a root canal infection, and people benefit from having their oral infections treated. Diagnosis
and treatment of oral infections belong to the central
and indispensable values of dentistry, and everybody
involved, not only patients, will benefit if prevention
and treatment of oral infections are at the core in the
dental profession. There is no solid scientific evidence
to distinguish among grades of periapical disease.
However, if the lesion is small and asymptomatic, the
probability of development of severe local symptoms
is low. Furthermore, in general, the health hazard of
an untreated persistent lesion is probably low.
Therefore, false-positive diagnoses should be avoided.
This first principle is simple but quite dogmatic. It implies that if a retreatment is suggested
following the diagnosis of a persistent lesion and
if this is accepted, no specific arguments or further deliberation are needed.
However, if a persistent lesion is diagnosed
and retreatment is not selected, specific arguments have to be put forward. These are found in
the second principle.
2. Second principle: A persistent periapical
lesion in a root-filled tooth might not be
retreated with regard to:
(a) Respect for patient autonomy
This principle implies that the patient is fully
informed regarding the situation but does not want
retreatment to be performed. Attitudes to periapical disease vary among individuals. The subjective
The potential risks (the probability of certain
negative events) associated with a possible
retreatment procedure (e.g. root fracture associated with post removal, nerve injury as a result of
periapical surgery) are objectively assessed and
weighed against the subjectively evaluated benefit resulting from retreatment. The risk/ benefit
ratio is found to be too low to be accepted.
(c) Retreatment monetary costs
Patient’s costs for retreatment are considered
(e.g. treatment fee, drugs, loss of income, suffering), and the cost/benefit ratio is subjectively
considered to be too low to be accepted.
6.8
urgical or Nonsurgical
S
Retreatment
While the clinician makes a diagnosis and
informs about and considers retreatment of a persistent apical lesion to the patient, the question, if
so, how is a natural and integrated part of the
process.
There is insufficient scientific support on which
to determine whether surgical and nonsurgical
retreatment of root-filled teeth gives systematically different outcomes, both short and long term,
with respect to healing of apical ­periodontitis or
tooth survival [56, 57]. In everyday clinical practice, a number of factors influence the choice of
retreatment method. For example, the size of the
bone destruction, the technical quality of previous
treatment, accessibility to the root canal, future
restorative requirements of the tooth, the cost of
treatment, the preferences of the clinician and the
patient, m
­ edical considerations and the availability
6
Decision Making
of various types of special equipment are briefly
discussed below. More detailed discussion is available in Chaps. 7 and 8. Although future comparative studies may provide valuable general
information, clinical decisions in every individual
case will still have to be made on the basis that the
conditions applying to every case are unique.
6.8.1
he Size of the Bone
T
Destruction
Apical periodontitis may develop into cysts.
Periapical cysts are classified as “pocket cysts” or
“true cysts”. In case of a pocket cyst, the cyst cavity is open to the root canal, and therefore it is
expected to heal after proper conventional root
canal treatment. The cavity of a true cyst, on the
other hand, is supposed to be entirely enfolded by
epithelial lining which may make it nonresponsive to any nonsurgical root canal treatment or
retreatment. Thus, it is supposed that true radicular cysts have to be surgically resected in order to
heal [58]. There is no method to clinically determine the histological diagnosis of the periapical
tissue in general, and in particular there is no
method to discriminate between pocket cysts and
true cysts [59]. Cysts are expected to be more
prevalent among big bone destructions [60].
The clinical empiric support for how radicular
cysts are best treated is poor but rather based upon
histological findings and theoretical assumptions.
However, in cases when a big (≥ 15 mm in diameter) periapical bone destruction is present and
especially if the quality of the root filling is good,
these assumptions suggest there are reasons to
suspect a “true cyst” and consequently consider
surgical retreatment as the first choice.
6.8.2
he Technical Quality
T
of the Previous Treatment
In cases of non-healed apical periodontitis, the
quality of the initial root treatment is often inadequate. This is frequently reflected in the poor
technical quality of the root filling [61]. In
molars, the reason for treatment failure may be
associated with untreated canals [62]. In many
67
cases, therefore a nonsurgical retreatment should
be considered. In particular, this is the case when
access is not obstructed by a crown and post.
Since there is convincing support that the quality
of the restoration also plays a significant role for
the periapical status in root filled teeth the clinician should always have a critical look at the
restoration.
The obvious objective for a nonsurgical retreatment is to treat previously untreated parts of root
canal system and thus improve the quality of root
canal filling. With the help of modern endodontic
armament, this is often possible to achieve.
Studies have shown that nonsurgical retreatment
performed by skilful clinicians results in good
chances of achieving periapical healing [63, 64].
It is sometimes argued that the result of a surgical of endodontic surgery is dependent of a good
quality of the root filling and consequently that any
endodontic surgery should be preceded by a nonsurgical retreatment. The benefits of this approach
must be questioned. The evidence base is weak
[65]. And even if the procedures would show marginally better healing outcome, the cost-effectiveness must be questioned. Moreover, if used orderly
it would lead to the execution of a not insignificant
amount of unnecessary surgeries. In many cases
the nonsurgical treatment would be sufficient to
achieve healing of the periapical tissues and consequently making the surgical procedure redundant.
6.8.3
Accessibility to the Root Canal
Root-filled teeth are often restored with posts and
crowns and are frequently used as abutments for
bridges and other prosthodontic constructions
which have to be removed or passed through for a
nonsurgical approach. In cases where the quality of
restorations is adequate, therefore, the more
­complex the restoration, the more appealing an endodontic surgery approach. Even without hindering
restorations, a preoperative analysis of the case may
reveal intra-canal ledges or fractured instruments
that already preoperatively make the accessibility to
the site of the residual infection questionable [63].
On the other hand, access to the site of infection by endodontic surgery can also be judged to
imply major difficulties. In particular surgery
T. Kvist
68
involving mandibular molar roots as well as palatal roots of the maxillary teeth sometimes offers
significant operator challenges. Preoperative
CBCT scans help the surgeon to plan the intervention or sometimes to refrain and choose a nonsurgical approach or even considering extraction and
a different treatment plan [66].
ment. Since posts and crowns have to be removed
(and replaced), a nonsurgical approach will be
expensive in such situations. Indirect and intangible costs associated with endodontic retreatment
are mainly related to postoperative sequelae such
as pain and swelling [72].
6.8.6
6.8.4
Restorative Requirements
of the Tooth
Before considering retreatment of a previously
root-filled tooth, there is a need for a careful
deliberation of the overall treatment plan. In
many cases the issue is rather straightforward. It
might concern a single tooth, restored with a post
and a crown of fully acceptable quality but with
an ensured diagnosis of persistent apical periodontitis. The objective is to cure the disease and
to “save” the tooth and its restoration in the long
term. In other situations, when complete mouth
restorations are planned to “build something
new”, the strategic use of teeth, non-root filled as
well as root filled, and dental implants to minimize the risk of failure of the entire restoration
must be the first priority [67]. Long-term follow­up studies of teeth that have undergone surgical
or nonsurgical retreatment are rare [68–70].
6.8.5
The Costs
Since surgical endodontics does not require the
dismantling of functional prosthodontics constructions, it is often a less expensive alternative for the
patient. But the costs of both surgical and nonsurgical treatment of course vary both in different
countries between operators and between countries with different systems of reimbursement by
insurance. From a patient’s point of view, three
types of monetary costs associated with endodontic retreatment may be considered: (i) direct costs
(dentist’s fees, drugs), (ii) indirect costs (patient’s
loss of income) and (iii) intangible costs (monetary value of the patient’s pain and suffering) [71].
The presence of prosthodontic reconstructions
will often impede access for nonsurgical retreat-
The Preferences
of the Clinician
and the Patient
Whether a retreatment, nonsurgical or surgical,
should be performed is a complex decision making situation. Many factors have to be considered.
For the dentist who made the diagnosis and who is
about to suggest a treatment alternative, both biological considerations and the potential and limitations of different options have to be deliberated
[73]. However, as important the professional skill
and knowledge might be the preferences of each
individual patient will also influence the final
decision. Only the patient is the expert on how he
or she feels about the pros and cons with different
retreatment options, which risks are tolerable and
what costs are agreeable.
Take-Home Lessons
• Clinical decision making of apical periodontitis in root filled teeth is a complex
task and that different decision-makers
come to different decisions depending
on different circumstances in different
situations is not only understandable but
also necessary and desirable.
• In the situation of making a diagnosis,
avoid false-positive diagnoses.
• When the diagnosis of persistent apical
periodontitis is clear-cut, from the dentist’s and profession’s point of view, with
current available knowledge, a suggestion of retreatment is the first principle.
• Include the patient in the decision making
process, and when refraining from action,
refer to any of the grounds of the second
principle, autonomy, risks or costs.
6
Decision Making
Benchmark Papers
• Reit C, Gröndahl HG. Management of
periapical lesions in endodontically treated
teeth. A study on clinical decision making.
Swed Dent J. 1984;8:1–7. In this study the
variation in clinical decision making of
root-filled teeth with apical periodontitis is
illustrated exemplary and clearly.
• Kvist T. Endodontic retreatment. Aspects
of decision making and clinical outcome.
Swed Dent J Suppl. 2001;144:1–57. In
this doctoral thesis several of the aspects
of decision making in endodontics are
elaborated.
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7
Surgical Retreatment
Peter Jonasson and Magnús Friðjón Ragnarsson
It ought … to be understood that no one can be a good physician who has no idea of
surgical operations, and that a surgeon is nothing if ignorant of medicine.
—Guido Lanfranchi
Chirurgia Magna (1296, printed 1479).
Abstract
In many cases, modern surgical retreatment technique is a realistic treatment option with a predictable and successful outcome. The main objective with surgical retreatment is to eliminate and prevent bacterial infection
in the root canal system from causing an inflammatory reaction in the
periradicular tissue. This chapter provides an overview of possible indications and contraindications for surgical retreatment from a technical, biological, anatomical, and medical perspective.
The concept of minimal invasive microsurgical approach is the state-­
of-­the-art for surgical retreatment. It requires certain techniques, instruments, and materials. Furthermore, and perhaps most importantly, it
requires magnification and illumination either through an operating microscope or loupes equipped with head-lights.
A basic prerequisite for successful treatment is the diagnosis, case
selection, and treatment planning. This is particularly important since the
primary treatment has failed, and consequently, the case may pose particular difficulties, which is exemplified in the chapter.
7.1
P. Jonasson, DDS, PhD (*)
Department of Endodontology, Institute of
Odontology, The Sahlgrenska Academy,
University of Gothenburg, Göteborg, Sweden
e-mail: peter.jonasson@odontologi.gu.se
M.F. Ragnarsson, DDS
Endodontist in private practice, Reykjavik, Iceland
© Springer International Publishing AG 2018
T. Kvist (ed.), Apical Periodontitis in Root-Filled Teeth,
https://doi.org/10.1007/978-3-319-57250-5_7
Introduction
Over the years, endodontic surgery has greatly benefited from a continuing technological development.
With the skilful use of the operating microscope,
ultrasonics technique, and root-end filling materials
such as MTA, tooth maintenance after endodontic
surgical procedures has become predictable, and the
success rate has improved [1, 2]. The indications for
73
P. Jonasson and M.F. Ragnarsson
74
surgical retreatment have been extended from
being considered to be the last resort to a viable
alternative to orthograde retreatment in most
cases. The main objectives of any endodontic
retreatment procedure are long-­term survival of
an asymptomatic tooth and healing of the periapical tissues. Using a surgical retreatment
approach, this is achieved by reducing the bacterial load and preventing bacterial leakage from
the root canal system into the periradicular tissues. Modern endodontic surgery technique has
the potential to effectively eradicate the causes of
persistent apical pathology with little postoperative discomfort [3, 4].
The advantages of a surgical rather than non-­
surgical approach to persistent apical periodontitis in root filled teeth include:
• Preservation of coronal tooth structure.
• No need for drilling through or removing
prosthodontic restorations.
• Root and surrounding tissues are directly
visualised for diagnosis and interventions.
• A biopsy of the pathological tissue may be
taken and sent for a histological examination.
However, there are also some obvious
disadvantages:
• Lack of control of possible coronal leakage
and carious lesions under restorations
• Limited access to the root canal full length
• Limited possibility to use chemical disinfection methods
7.2
Indications,
Contraindications,
and Treatment Planning
The goals for endodontic surgery are to retain a
tooth in function without signs and symptoms of
persistent infection. Unfortunately, there is no solid
scientific evidence to choose between surgical and
non-surgical treatment with respect neither to healing of apical periodontitis, tooth survival nor cost
effectiveness. Every case is unique and the decision
has to be made on an individual basis.
In cases where apical periodontitis persists
after conventional endodontic treatment, the first
step is, together with the patient, to evaluate the
tooth’s value from a functional and aesthetic
aspect. The individual preferences are likely to
vary greatly and may be the single most important factor for the final decision.
The evaluation before treatment must always
include a careful weighing of the advantages and
disadvantages as well as a cost-effectiveness
analysis of the treatment options. The importance
of proper diagnosis cannot be overemphasised.
The examination comprises a thorough clinical
and radiographic examination, including adjacent and opposing teeth, in order to decide
whether surgical or non-surgical retreatment
should be the treatment of choice.
Trying to analyse and to understand the underlying mechanisms that apical periodontitis is not
healing and where the causative infection is
located is of paramount importance for the proper
management. Infections causing apical periodontitis can either persist after endodontic treatment
or be a recurrent infection from coronal leakage.
In some cases, an extraradicular infection may be
suspected. Large periapical lesions are likely to
be bounded by epithelium, i.e. a radicular cyst
may have been formed and a surgical retreatment
may be necessary to remove the tissue to establish a proper diagnosis and optimise the likelihood of healing.
Besides these basic assessments, several other
considerations must be made by the wise clinician.
7.2.1
Technical Considerations
It is generally accepted that the healing of the periradicular tissue after orthograde endodontic treatment
is positively correlated with the technical quality of
the root filling and coronal restoration [5–7].
Before evaluating the technical aspects of the
present root filling, it is of great importance to
evaluate the quality of the coronal restoration.
7
Surgical Retreatment
75
If the quality is poor (over- or under-extended
restorations) or if secondary carious lesions are
present, this may suggest that the origin of persistent disease originates from coronal leakage. If
so, non-surgical retreatment including a replacement of the restoration appears mandatory in
order to fulfil the objectives of retreatment.
However, in many situations the coronal restoration is judged to be functional and without
major defects, but the quality of the root filling is
poor. Consequently, it is reasonable to assume
that the source of failure comes from a persistent
infection within the root canal system. A basic
prerequisite for successful outcome is accurate
access to the site of infection.
From this perspective, non-surgical retreatment generally provides better accessibility to
treat and refill the complete root canal system.
Consequently, selecting this option seems attractive especially when the clinician judges that
quality of seal can be substantially improved.
However, to remove an existing restoration for
better accessibility for orthograde retreatment
a
b
Fig. 7.1 (a) Radiograph of an upper lateral incisor with a
long parallel post showing an incomplete root canal filling
and a periapical radiolucency. Endodontic treatment
options can either be conventional retreatment after
removal of crown and post or surgical retreatment.
Considering the relative narrow root in relation to the size
of the post and possible risk for inducing root fractures,
can imply great differences in costs, technical
difficulties and risks to induce complications.
Even if the risks for technical complications and
inducing root fracture appear small when removing posts, on the basis of the limited data available in the literature [8], the decision must be
based on root and post dimensions, type of post
and the technique for removal [9] (Fig. 7.1). In
case the access preparation is made through the
artificial crown, it may influence the retention
and provoke loosening of the cemented crown
[10, 11] and result in a situation where the crown
and/or bridge have to be replaced. Incomplete
root fillings should as far as possible be handled
with orthograde retreatment.
On the other hand, irrespective of the quality
of the former treatment, surgical retreatment is
considered to be the first choice where orthograde retreatment has failed to control the infection or cannot be undertaken due to blocked
canals caused by dystrophic calcifications and
iatrogenic errors such as ledges, broken instruments and presence of posts (Figs. 7.2 and 7.3).
c
surgical retreatment is considered as the first choice of
treatment. (b) The retrograde instrumentation of the canal
was performed with hand files held in a haemostat. To
maintain the curvature of the canal flexible files can be a
better alternative than stiff ultrasonic tips when longer
instrumentations are needed. (c) Postoperative radiograph
with a retrograde filling to the level of the post
P. Jonasson and M.F. Ragnarsson
76
a
b
Fig. 7.2 (a) A lower left first molar with an incomplete root
filling and periapical radiolucencies on booth roots. Surgical
retreatment was performed as an alternative to conventional
retreatment. A partly or completely obliterated mesial root
can be suspected from the radiograph that can be challenging
to treat. The patient was eager to keep the crown and post in
a
b
c
order to reduce the costs. (b) A postoperative radiograph with
a limited retrograde preparation and filling in the mesial root.
(c) Five years postoperatively, the patient developed pain from
the area. The radiograph showed a nice bone healing on the
first molar, but the second molar had developed a periradicular bone lesion found to originate from a root fracture
c
Fig. 7.3 (a) Radiograph of the upper left first molar with
a fractured instrument in the mesiobuccal root diagnosed
with symptomatic apical periodontitis. Due to the difficulties in removing instrument without extensive risks for
complications when located in the apical third of the root
with a root curvature, surgical retreatment was performed.
(b) Immediately postoperatively. (c) A 1-year follow-up
7.2.2
for cystic lesions [18, 19]. Based on histological
criteria, two different categories of cysts have
been defined [20, 21]: True cyst which have complete enclosed lumina and therefore no direct
connection to the root canal and pocket cysts that
have open connection to the root canal. True cyst,
different from pocket cysts, may therefore be
self-perpetuating and fail to heal if not treated
surgically.
Foreign body material can accidentally be displaced to the periapical tissue during endodontic
treatment. The presence of a foreign body in the
periapical tissues may cause endodontic failure
by triggering an inflammatory response and a
subsequent foreign body reaction, which can be
treated successfully by surgical retreatment.
A local deep pocket is generally an aggravating factor for the prognosis (Figs. 7.4 and 7.5).
Tentative diagnoses are periodontal fistulation,
root fracture or an endo-perio lesion either
caused by primary or secondary periodontal disease. The benefits with a surgical approach are
Biological Considerations
From microbial perspective, surgical retreatment
is indicated when suspecting a persistent infection
withstanding the effect of an impeccable root
canal treatment. Even though persistent infections
are mainly localised in the root canal system,
microorganisms can establish an extraradicular
infection formed as a biofilm on the root surface
adjacent to the root apex and even colonizing the
periapical tissue [12, 13]. However, to what extent
an extraradicular infection can persist without the
intraradicular infection as a reservoir is not well
understood [14] and a surgical retreatment should
therefore focus on treatment of all possible infection sites.
Most periapical lesions can be classified as
dental granulomas, root cysts and abscesses [15,
16]. Periapical lesions cannot be differentiated
based only on the radiographic observations [17].
However, a correlation has been shown between
the radiographic lesion size and the probability
7
Surgical Retreatment
77
b
a
c
Fig. 7.4 (a) First lower right molar with a persistent
pathology after orthograde retreatment. (b) Adjacent to
the fistula a local pocket was probed to the apex. No root
fracture could be found after exploration. (c) The radio-
a
b
Fig. 7.5 (a) Upper right second premolar with a deep
pocket located buccal. (b) An exploration was made in
order to inspect the root surface. (c) A vertical fracture
graph shows a periradicular radiolucency on the mesial
root. The mesial root was surgically retreated with a questionable prognosis then it is difficult to know if a secondary periodontal lesion had developed
c
line was found after removing the soft tissue and staining
with methylene blue
P. Jonasson and M.F. Ragnarsson
78
the ­possibilities to explore the root and evaluate
for eventual fractures and supplement if necessary with a periodontal treatment.
With an extensive marginal attachment loss in
periodontally compromised teeth, the possibilities to perform a surgical treatment may be limited. Osteotomy for apical resection reduces
longitudinal width of the buccal bone that
increases the risk of endo-perio communication.
Moreover, with the surgical approach, the apical
part of the root is resected and the crown-to-root
ratio of the tooth may be unfavourable for the
prosthodontic prognosis. The evaluation of tooth
mobility preoperatively and the bite forces can be
crucial to the possibilities of treatment.
7.2.3
Anatomical Considerations
A preoperative judgement of the accessibility of
the site of infection is central for the successful
outcome of the procedure. Careful evaluation of
two or more periapical radiographs exposed in
different angulations is mandatory (Fig. 7.6), and
for certain cases, computed tomography is a good
complement for planning and performing the
treatment (Fig. 7.7).
Most roots are accessible for surgical treatment. In the lower jaw, proximity to the mandibular nerve and/or a thick cortical bone buccal to
the tooth may limit the accessibility. Extended
a
Fig. 7.6 An upper molar with a symptomatic apical periodontitis. (a) The radiographs showing a periapical radiolucency and fractured instrument in the apical third of the
mesiobuccal root. (b) With a mesial eccentric radiographs,
p­ reoperative radiographic examination with cone
beam computed tomography CBCT is recommended in such cases. The palatal root can either
be treated by a buccal or palatal entrance. The relation to sinus and indications for treating the buccal
roots is crucial for the decision (Fig. 7.8). A palatal
entrance is technical demanding not at least
depending on the difficulty raising the flap and get
a good insight (Fig. 7.9). In cases were the accessibility to the palatal root is limited surgically
especially for the second maxillary molars, a combined intervention may be considered with a conventional orthograde treatment of the palate root.
The location of the lesion, root anatomy, relationships of roots and relation to neighbouring
anatomical structures and findings that indicate
untreated channels are of special interest for
treatment planning. Once again, CBCT is a powerful tool that can assist when a more exact three-­
dimensional imaging of the tooth and the
periapical tissue is necessary [22] (Fig. 7.7).
For supporting the clinician in the preoperative planning, a guide with different categories of
complexity of lesions has been presented [23]
where the more severe categories are demanding
and may need certain surgical skills, techniques
and equipment.
The location of the root in the alveolar process
and possible involvement of neurovascular structures may hamper the opportunities for access.
Nerve injuries and altered sensation is however
b
the root-filled canal in the mesiobuccal root moves from
the x-rays, not centralised in the canal, indicating a second
untreated canal
7
Surgical Retreatment
Fig. 7.7 Orthopantomogram showing a patient with need
of extensive fixed prosthodontic treatment. Evaluation of
suitability of the upper jaw for installing implants showed
poor bone conditions. The radiographic examinations
showing periapical radiolucencies on several teeth (13, 22
and 26). Thirteen and twenty-six are restored with well-­
functioning posts and not planned for removal. Surgical
79
retreatment was planned. A CBCT in axial, frontal and
sagittal view and periapical radiograph of the first left
maxillary molar showing periapical radiolucencies around
all roots. In between the roots there is a sinus recess. Only
a minor swelling can be seen in the sinus mucosa. The
postoperative radiograph showing the retrograde fillings
performed by a buccal entrance
P. Jonasson and M.F. Ragnarsson
80
a
b
c
d
e
f
Fig. 7.8 Surgical treatment of tooth 26 was performed by
a buccal entrance. (a) After removing the soft tissue and
performing the root resection of the buccal roots a perforated sinus membrane was found. (b) As the sinus membrane was perforated, access to the palatal root could be
achieved from sinus. The arrow showing the apex of the
palatal root covered by the sinus membrane and bone. (c)
The palatal root is seen after drilling through the covering
tissue. (d) The palatal root after root resection. (e)
Inspecting the mesiobuccal root by a micro mirror. The
root filling in the canal showing a void. Parts of the isthmus in between the canals are seen. (f) Gauze is packed
into the sinus in order not to introduce infected material or
inadvertently drop instruments into the sinus. The canals
and the isthmus are prepared by a contra-angled ultrasound tip
rarely reported after surgical retreatment. It can
occur as an effect of nerve traumatised during
surgery or following local anaesthetic administration, or indirectly caused by a postoperative
inflammation when performing treatment in the
vicinity of major nerves. The risk to injure the
inferior alveolar nerve is related to treatment of
second molar and premolars but also to some
extent first molars [24].
Surgical treatment on teeth with apex or a
periapical lesion in close apposition to the maxillary sinus should be carried out with caution
(Fig. 7.8). Removal of infected tissue should be
performed carefully, in order to avoid perforation
of the sinus membrane.
Sometimes the membrane is disrupted due to
the inflammatory reaction. In such cases, special attention has to be made to not introduce
infected material or inadvertently drop instruments into the sinus. This can be prevented by
packing the sinus with gauze. A final thorough
rinsing with saline is important to ensure
removal of infected material in the sinus.
More extensive lesions that have destructed
the cortical bone plates with a through-and-­
through lesion may end up with incomplete bone
healing with fibrous tissue ingrowth (scar tissue)
[25] (Fig. 7.10). A situation that may be only
indication for where a guided tissue regeneration
technique may be indicated [26].
With larger lesions, other tissue structures distant from the tooth may be involved and can complicate the treatment and certain precautions have
to be made. More teeth may be necrotic and
involved in the process and therefore the vitality
of neighbouring teeth has to be evaluated before
surgery. Due to the surgery and soft tissue curettage teeth not involved in the process may be
devitalised due to the treatment.
Radiographic evaluation of the size and the
location of the bone lesion may give an indication
to where in the root the infection is localised. An
7
Surgical Retreatment
81
a
b
Fig. 7.9 (a) First left maxillary molar with an apical functioning crown, a surgical retreatment was planned.
radiolucency related to the palatal root according to the (b) Showing the palatal flap and the fenestration of the
intraoral radiograph. Due to long post and a well-­ palatal bone plate
a
b
c
Fig. 7.10 A sequence of healing after surgical retreatment of tooth 12. (a) Immediately postoperatively (b) A
1-year follow-up with a reduction of the defect in the
bone. (c) A 4-year follow-up showing a feature of incomplete scar tissue healing with continuous periodontal ligament and a separate lesion
important question is whether lateral canals or
untreated canals may be involved (Figs. 7.6 and
7.11), and if these are accessible for treatment
during surgery. Also, any external inflammatory
root resorption that may have occurred should
also be localised and held as a potential exit of
intra-canal infection when treating the root.
Even if the impression from the intraoral
radiographs is that the tooth has separate root
canals, anatomical studies have shown a great
variety in morphology and complexity of the
canal system [27]. Canals may branch, divide and
rejoin, end in apical ramifications and have accessory canals and roots with more than one canal
having isthmuses (Fig. 7.8). All these anatomical
sites may function as a bacterial reservoir and are
crucial to properly treat.
Where there is poor supporting bone tissue
surgical retreatment may be contraindicated due
to the doubtful prognosis. Teeth with endodontic-­
periodontal lesions may exist separately and
later unite together in a combined lesion, or it
may be primarily endodontic or periodontal with
a secondary involvement of the other (Fig. 7.4).
P. Jonasson and M.F. Ragnarsson
82
Fig. 7.11 (a) An upper
right canine with a
juxtaradicular
radiolucency. (b) A
lateral canal (arrow) was
located after exploration
and staining with
methylene blue
a
b
Fig. 7.12 Upper right canine with a long post and juxtaradicular and periapical radiolucency. An exploration
showing a buccal post perforation. The perforation was
covered by a composite with a dentine bonding agent after
drilling a minor cavity
Due to the risk for down growth of a long junctional epithelium and subsequent hindrance of a
favourable healing with bone and reattachment,
the outcome is compromised [28, 29].
In cases with long posts especially in metal,
leaving a limited canal space may influence the
possibilities to perform enough deep retrograde
filling for a proper seal and alternative techniques
may be considered. This can also be the situation
in case of post perforation with limited possibilities to create a cavity preparation (Fig. 7.12).
7.2.4
Medical Considerations
Considerations of medical risks are essential for
all dental treatments but special precautions
should be taken when planning for surgery. For
every treatment, a risk assessment has to be performed based on a careful medical history and in
some cases after consultation with physician. For
medically compromised patients, orthograde procedures usually expose them to less medical risks
than surgical treatment. Therefore, a non-surgical
7
Surgical Retreatment
83
approach to endodontic retreatment may be more
suitable. For certain medical conditions, the surgical treatment should be postponed until the patient
has recovered. However, there are no absolute
medical contraindications to endodontic surgery.
An overall estimate of the medical risk can be
made due to the physical status classification system adopted by the American Society of
Anaesthesiologists (ASA) in 1962 with a modification in five categories to the dental treatment
situation [30].
There are several medical conditions and
medications that cause a depressed immune system, where surgical intervention is contraindicated until white blood cells count and antibody
levels have normalised.
Patient with increased risk for bleeding needs
special attention. Medication with antiplatelet
and anticoagulant agents increases the bleeding
time intra- and postoperatively. Surgical treatment is possible in most cases but needs certain
treatment protocols. Surgical treatment of
patients with haemophilia or impaired liver function should only be after consultation and in
agreement with the patient’s physician.
Previous high-dose irradiation affects the
blood vessels and reduces the blood supply to the
jawbone. An irradiated bone must be treated with
caution, as there is always a risk of reduced healing potential, developing postoperative infection
and osteoradionecrosis and surgical treatment
a
b
Fig. 7.13 Single-rooted maxillary incisor treated by surgical retreatment using microsurgical technique. (a) The
resected root and canal with gutta-percha seen in the micro
should only be performed after careful consideration of the alternatives.
Osteonecrosis is a rare condition and has mainly
been related to intravenous delivery of bisphosphonates in patients with bone cancer disease [31].
Invasive treatments have been shown to increase
the risk of developing this serious complication.
However, few cases have been reported and very
few guidelines are available in the endodontic literature. Even if no evidence-­based data are available, non-surgical retreatment seems to be
preferable, but as an alternative to extraction, surgical retreatment still is a less traumatic procedure.
7.3
Methods and Techniques
Endodontic surgery has developed from a surgical procedure where a curettage and removal of
the soft tissue surrounding the root apex was the
only action towards a causal oriented approach
with the aim to eradicate or closing in the root
canal infection. Untreated infected parts of the
root canal system are localised and mechanically
treated. Persistent infections in inaccessible areas
are instead entombed with a retrograde filling
preventing leakage of microorganisms and their
by-products into the periradicular tissue.
Today’s state-of-the-art is a minimal invasive microsurgical approach that requires particular skills, techniques (Fig. 7.13), instruments
c
mirror and microscope (x6) with good haemostatic control.
(b) Retrograde preparation with a contra-angled ultrasonic
tip (3 mm). (c) Application of the retrograde filling (MTA)
P. Jonasson and M.F. Ragnarsson
84
and materials. Magnification with loops or most gingiva should be taken. In order to minimise the
preferable a surgical operating microscope is risk, a submarginal incision is often recommended. However, if the anatomical conditions
mandatory.
The surgical microscope and micro-­are not favourable or if the surgery is not well
instruments are an integral part of the up-to-date performed, such an incision may have devastatendodontic surgery arsenal. Its’ combination ing effects on the aesthetic outcome; that’s why
with an essentially improved illumination due to this technique should be used with caution. The
the built-in light source has improved the possi- biotype of gingiva can predict the risk for recesbility to see, localise and hence also treat the vari- sion. A thick and wide papilla compared to a thin
ous locations of microbes present in and on the and narrow is more likely to heal without recesroot. As a consequence, the indications for end- sion [33]. Important factors for the healing proodontic surgery have expanded [32]. With a bet- cess are also a healthy gingiva and the level of the
ter understanding of infection control and more marginal bone supporting the soft tissue during
conservative handling of the soft and hard tis- the healing process.
sues, the reported success rate has significantly
been improved.
7.3.2
7.3.1
Bleeding Control
During Surgery
Soft Tissue Management
To get access to the root, the surgery commences
with an incision and raising of a full-thickness
flap. This means a soft tissue flap, which entails
gingival and mucosal tissues as well as periosteum. Many different flap designs have been proposed in the literature [33]. The objective is to
provide good accessibility and view without
unnecessarily traumatise soft tissue in order to
promote a predictable healing of gingival tissue.
The design of the flap should be carefully planned
in advance and has to be adapted to each individual and case. To be able to mobilise the flap,
various modes of incision can be selected, including horizontal incisions and vertical releasing
incisions. The horizontal incision can either follow and include the papilla or cut through the
papilla base. The most frequent horizontal incisions are either sulcular with or without involving the papilla or submarginal in the attached
gingiva with one or two vertical releasing incision. The releasing incisions are performed parallel to the tooth axis and subperiosteal blood
vessels in order to minimise the number of cut
blood vessels.
In the aesthetic zone with artificial crowns,
precautions to reduce the risk for recession of the
Adequate bleeding control is crucial for inspecting the root and performing the retrograde treatment. An important first step for bleeding control
is to remove the highly vascularised granulation
tissue in the bone crypt. Local anaesthesia
­containing epinephrine contributes to a certain
haemostasis but must often be supplemented
with other medicaments. For certain patient
groups, epinephrine should not be used, and in
such cases, it is particularly important to have
access to other medicaments. However, cotton
pellet saturated with epinephrine for local use in
the bone crypt have been shown to be effective
for bleeding control and cause no changes in
blood pressure or heart rate [34].
Other topical haemostatic agents suggested
for controlling bone crypt haemorrhage are aluminium chloride or ferric sulphate [35].
A relatively common surgical complication is
an insult to blood vessels. In most cases, manual
compression will have adequate effect, but if
more severe bleeding, electrocauterization may
be considered.
Taken together there are techniques to control
local bleeding in most cases and is bleeding from
the site of endodontic surgery seldom a limiting
factor during the surgical procedure. For certain
7
Surgical Retreatment
groups of patients, special precautions should be
taken and a contact with the patient’s physician
for a dialogue about any preoperative measures
to prevent possible risks is recommended.
7.3.3
Root Resection
and Retrograde Treatment
of the Root Canal
The root resection is performed to eliminate
infected ramifications, lateral canals and contaminated dentin. Moreover, the root resection allows
better overview of the canal anatomy and inspection of the resected root surface for isthmuses or
microfractures. In general, a root resection of
3 mm apically is considered to be sufficient to
remove most of infected ramifications and lateral
canals [23]. It is optimally performed in a 90°
angle to the long axis of the root to minimise any
leakage that might occur through cut dentinal
tubules.
The aim of the root-end preparation is to
remove infected material and enough intra-canal
filling material to be able to seal the root canal
system with a retrograde filling. The ideal root-­
end preparation can be defined as a cavity of least
3 mm depth [36], with walls parallel to and coincident with the anatomic outline of root canal
space. Newer instruments have been designed to
prepare up to 9 mm in untreated canals or canals
with poor-quality root fillings [37]. In cases with
limited access and need of extended retrograde
instrumentation, hand files held in a haemostat
can be used as an alternative [38] (Fig. 7.1). The
purpose of the retrograde filling material is to fill
the apical canal space and to obtain a hermetic
seal and entomb microorganisms in not accessible areas. Numerous materials have been suggested for root-end filling include gutta-percha,
IRM, Super EBA and dentin-bonded modified
resins [39–42].
At the present time, mineral trioxide aggregate (MTA) is considered the gold standard for
root-end filling materials. But there is an emerging trend of using other bioceramic materials
85
[43]. MTA is a very appropriate material for root-­
end filling due to its good biocompatibility,
osteo- and cemento-inductive capabilities and
antibacterial and sealing properties [44–46]. The
drawbacks are long setting time and handling
difficulties.
Retrograde root-end cavities are prepared by
ultrasonic tips in exposed canal orifices that are at
least a 3 mm to provide a satisfactory thickness
and seal with MTA [47] (Fig. 7.13).
7.3.4
Suturing
After thorough irrigation with saline of the
wound surface for removal of contaminated
materials and blood clot a proper wound closure
is necessary for optimal healing. Surgical sutures
should hold the edges of a flap in apposition until
the wound has healed sufficiently to withstand
normal functional stresses and resist reopening.
Resorbable or non-resorbable threads in diameters 5-0 or 6-0 and three-eighths reverse-cutting
or tapered needle are commonly used. The
sutures can in most cases be removed after
7–14 days. If resorbable sutures are used, it
should retain resorption more than 7–14 days.
7.4
Postoperative Information
and Complications
Pain and swelling may occur after surgical treatment, but in most cases, only to a limited extent
[48]. The symptoms are related to the degree of
tissue trauma and inflammatory reaction. The
reaction is part of the healing process. In addition, secondary infection of the surgical site may
also occur and induce a postsurgical inflammation, which can sometimes be difficult to differentially diagnose from a normal postoperative
course.
Factors that have been shown to predispose
for postoperative pain are location for surgery,
poor oral hygiene, smoking and the duration of
surgery [49]. There is some data supporting that
P. Jonasson and M.F. Ragnarsson
86
surgical procedures lasting longer than 1 h predispose for postoperative symptoms and infections [50].
The severity of the pain is usually worst the
first 24 h postoperatively [49]. The swelling is
greatest between first and second postoperative
day. The management is usually prescribing anti-­
inflammatory analgesics (NSAIDs). In case of a
secondary infection, surgical drainage may be
required and if systemic effects and risk for
spreading prescription of antibiotics may be
motivated.
7.5
Prognosis
Successful treatment is defined by the absence of
radiographically and clinical signs of apical periodontitis. Within a period of 1–3 months, clinical
signs of pathology are expected to be missing,
and radiographically, a remineralisation of the
lesion and a new periodontal ligament formation
is expected to occur within 1–2 years. According
to the literature, the success rate for surgical
retreatment on accurate indications and using the
latest technical advancement can be expected to
be above 80–90% [32, 51].
Take-Home Message
• Surgical retreatment is a valid and predictable alternative for retreatment of
teeth with post-treatment apical periodontitis especially when it is desirable
to preserve a restoration.
• In cases where orthograde retreatment is
judged difficult or even impossible
because of previous iatrogenic errors or
blocked canals, surgical retreatment
may be the only realistic treatment alternative to extraction.
• Accurate diagnosis and correct treatment
planning is prerequisite for success.
• Using a minimal invasive microsurgical
approach for surgical retreatment
requires certain techniques, instruments,
materials and work with good vision for
a reliable treatment outcome.
Benchmark Papers
• Tsesis I, Rosen E, Taschieri S, Telishevsky
Strauss Y, Ceresoli V, Del Fabbro
M. Outcomes of surgical endodontic
treatment performed by a modern technique: an updated meta-analysis of the
literature. J Endod. 2013;39(3):332–9.
This review and meta-analysis paper
gives an updated evidence base for the
excellent healing frequencies that are
possible to obtain after surgical retreatment procedures in settings characterised
by extensive expertise, high clinical skills
and best available equipment.
• Kruse C, Spin-Neto R, Christiansen R,
Wenzel A, Kirkevang LL. Periapical
bone healing after apicectomy with and
without retrograde root filling with mineral trioxide aggregate: a 6-year follow­up of a randomised controlled trial. J
Endod. 2016;42:533–7. This clinical
study highlights the importance of the
retrograde filling for achieving good
healing results as well as the need for
more long-term follow-ups of surgical
retreatment procedures.
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periapical cysts and granulomas. Oral Surg Oral Med
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19. Lalonde ER. A new rationale for the management of
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8
Non-surgical Retreatment
Charlotte Ulin
If a thing is worth doing, it’s worth doing well
Abstract
Non-surgical retreatment is difficult and treatment planning is essential.
Good access to the already root-filled root canals and working with good
aseptic procedures will create a possibility to render a preferable prognosis. The knowledge and ability in how to remove the gutta-percha and
other obstacles within the root canal will make the procedure easier and
more predictable. The microbiotic flora in the already treated root canal
system with periapical pathologies is more robust to chemical treatment
due to its ability to survive in an environment where nutrients are sparse.
This is important to understand when making the choice of and how to use
the irrigant. An inter-appointment dressing is preferably used. The procedure of placing a new root filling might be as challenging as the removal
of the old one since the original form of the root canal has been changed.
Follow-ups of endodontic treatment must be made systematically and over
a longer period of time in order not to jump into conclusions or let rare
individual events distort the overall results.
8.1
Introduction
This chapter will describe a strategy in how to
treat root-filled teeth with a non-surgical
approach, what to consider, how to manage and
the expected result. The access to, the treatment
of and possible complications when treating the
root canal will be described.
C. Ulin, DDS
Specialist Clinic of Endodontics, Public Dental
Service Västra Götaland, Göteborg, Sweden
e-mail: charlotte.ulin@vgregion.se
© Springer International Publishing AG 2018
T. Kvist (ed.), Apical Periodontitis in Root-Filled Teeth,
https://doi.org/10.1007/978-3-319-57250-5_8
The aim of non-surgical retreatment is to get
access to and to eradicate the intracanal microorganisms responsible for the persistent apical periodontitis. In some cases the procedure is rather
pursued in order to improve the quality of root
filling in order to prevent apical periodontitis, for
example, prior to including the tooth in a prosthodontic construction.
Non-surgical retreatment challenges the clinician to repeat a procedure that has already been
done but to a higher standard and benefit for the
patient. It is well established that if the root filling
reaches 0.5–2 mm from the radiographic apex, has
no voids and follows the outline of the root canal,
89
C. Ulin
90
the prognosis of root canal treatment is good, and
healing or prevention of apical periodontitis will
prevail [1–3]. Therefore the first question to be
considered before starting the treatment is if you
think you are up for the challenge. Do you have the
clinical skills, the necessary armamentarium and
knowledge in how to conquer the obstacles that
might come in to your way?
In a systematic review [4] by SBU (Swedish
Council on Health Technology Assessment) published in 2010, they found that there is a lack of
evidence regarding the effect of different instrumental techniques, disinfection protocols or root
filling materials on periapical healing in conjunction with retreatment. Though, in essence, the
available evidence supports the current paradigmatic premise of endodontics that healthy periapical tissues are likely to be promoted if the
treatment procedures result in a successful eradication of the root canal infection.
The retreatment strategies include x-ray
examination, magnification and illumination,
coronal examination, access preparation, removing root filling material, irrigation and chemical
disinfection, placement of a new root filling restoration and follow-up.
8.2
X-ray Examination
Having good preoperative x-rays is crucial in creating the first attempt of creating a strategy for
non-surgical retreatment. With good x-rays the
a
b
Fig. 8.1 (a) Tooth 36 is symptomatic after root canal
treatment. (b) X-ray in distal angulation suggests the presence of an untreated mesial-lingual canal. (c) Reamer 02
preoperative status of the treated tooth of choice
can be studied. Are there signs of caries, posts,
untreated root canals and procedural errors such
as instrument fractures, ledges and overinstrumentation? The status of the root filling can be
visualized. Is it short? Are there voids or unfilled
spaces? Does it follow the original anatomy of
the root canal? The answers to these questions
will give a preview of the challenges of treatment
ahead.
Two apical intraoral x-rays in different angulations are mandatory. “One x-ray makes you
interested, with two diagnosis can be made”
(Fig. 8.1). Sometimes a bitewing is necessary to
diagnose caries and status of the coronal restauration. With a bitewing x-ray the risk of over- or
under-axial angulation is avoided. Hereby some
of the above questions can be answered and some
can be enlightened.
Cone beam computed tomography (CBCT) is
a very useful tool in diagnosing periapical lesions
and root canal anatomy. It has its disadvantages
in already root-filled teeth due to the creation of
artefacts from the root filling material and also if
posts are present (Fig. 8.2). The European endodontic society made a position statement in
2014 [5] regarding the use of CBCT in endodontics. “A request for a CBCT scan should only be
considered if the additional information from
reconstructed three-dimensional images will
potentially aid formulating a diagnosis and/or
enhance the management of a tooth with an endodontic problem(s)”.
c
ISO 15 in mesial-lingual canal verifies the likely reason
for case being symptomatic
8
Non-surgical Retreatment
91
Fig. 8.2 Cone beam
computed tomography
(CBCT) has its
disadvantages in
root-filled teeth due to
the creation of artefacts
from the root filling
material and also if posts
are present
8.3
Magnification
and Illumination
Magnification and illumination in endodontic
practice is a good help within any step of the
procedures. The possibility to visualize the
tooth and root canal system will give diagnostic
information, and during treatment the surgical
microscope makes the procedures easier and
allows them to be conducted in a controlled
manner. The clinical effect of the use of the surgical microscope is difficult to evaluate from a
strictly scientific point of view, and there are no
studies available that specifically investigated
the outcome of orthograde retreatment if or not
using an operating microscope, although the
possibility to enhance the quality of the access
preparation in terms of locating root canals has
been studied [6–8].
8.4
ssessment of the Coronal
A
Restoration
A root-filled tooth has usually a large coronal restoration or an artificial crown. The status of the
coronal restauration needs to be assessed for
­several reasons. Gaps between the filling material
and the dentine or carious lesions may be the
source of persistent apical periodontitis through
the mechanisms of coronal leakage. Consequently,
in such a situation, all filling materials and soft
dentine have to be removed to create aseptic conditions during treatment and to allow for a successful outcome in the long term.
In some situations the quality of the crown or
restoration is judged to be faultless, and it seems
to be safe to carry out the treatment with the
maintenance of the restoration from a microbiological point of view. However, a proper access
to the root canal system may be jeopardized.
Hence a complete removal of the previous filling or artificial crown may be indicated
anyway.
After the complete removal of the restoration
and caries, the ability of the remaining tooth substance to provide support for a new restoration
must be assessed. Not surprisingly, it is common
for this appraisal to turn out negatively and the
tooth is deemed for extraction. Therefore, the
patient should be informed that the decision to try
to cure a tooth by retreatment might be due to
change as treatment commences and progresses.
Another common finding is that remaining tooth
structure is compromised by cracks or fractures.
In conjunction with a local periodontal pocket, it
gives reasons to believe that a vertical root fracture is present. Also under such circumstances,
the retreatment is pointless and the tooth should
rather be extracted. When only minor cracks
C. Ulin
92
without any periodontal involvement or mobility
between s­ egments are present, the clinical decision is more difficult. There is only scarce scientific documentation on the long-term outcome.
The prognosis should be considered doubtful. If
the treatment is carried on, it must be after thorough deliberation and informed consent from the
patient.
The coronal examination also involves an
inspection of the pulp chamber floor. The possible presence of untreated root canals or isthmuses can hereby be diagnosed. For example,
65–98% of the upper first molars have two root
canals in the mesiobuccal root [9, 10]. And the
most palatal of the two (MB2) has frequently
been overlooked in the primary treatment and
may be the underlying reason to treatment failure. The presence of previously made perforation in the pulp chamber can be diagnosed. If
diagnosed the prognosis is dependent on the
created damage to the periodontium and the
possibility to successfully seal the area of perforation [11, 12].
The type of root filling material previously
used can also be assessed. There are many different types of root filling materials used.
However, in most cases the clinician will find
canals filled with some type of sealer together
with a core of gutta-percha. But sometimes
only sealers or cements have been used. Core
materials other than gutta-percha such as silverpoints or plastic carriers may also have
been used. Tooth colouring can sometimes
give a hint about what materials have been
administered. A pink-coloured tooth is usually
root filled with resorcinol-formaldehyde resin,
so-called Russian red [13].
8.5
emoval of Crowns, Cores
R
and Posts
The removal of a crown will almost always
also remove some dentine since the border
between the crown and the underlying dentine
is difficult to visualize. The crown is most
e­ asily removed by drilling an axial furrow on
the buccal side in to the dentine. The cemental
lock is then breakable by creating a bending
force inside the furrow with, for example, a
small and short screwdriver or a carver.
Depending upon the core material of the crown,
it will be more or less challenging. There are
today burs available that are designed to cut
through given materials such as titanium, zirconium, cobalt-chrome, etc. A high-speed
hand-piece should be avoided due to its low
momentum. An upregulated air-turbine-driven
hand-piece is preferable.
Sometimes a core and post might be present
inside the prosthodontic construction or even
when there is a composite resaturation. The
core is removed with burs. If a post is present,
it can be of metal or a fibre material. Depending
on the fit and retention of the post the removal
might be quick or time consuming. The aim is
to dislodge the lock of the cement surrounding
the post after which it will become loose and
easy to passively remove. This is preferably
done by ultrasonic equipment even though
other techniques are available. The coronal
part of the post, above the orifice of the root
canal, must be exposed. It is important to make
sure that the core material is removed from the
post. After choosing an ultrasound tip, designed
for the purpose, this is placed against the post,
and the ultrasonic unit is set on a high frequency. Then, the clinician moves the tip
around the post in order to allow the vibrations
to be transported along the post and break the
cement. Thin ultrasonic files can be used to
remove the cement between the root canal wall
and the post. If the post does not come loose,
the possibility of drilling away the post can be
considered. There are specially designed burs
to at a low speed remove fibre posts. The risk
of at the same time removing dentine and
increasing the risk of root fracture or perforation has to be taken into account. Magnification,
visibility, acquaintance of the root canal anatomy and skill is obviously crucial for a successful result.
8
Non-surgical Retreatment
8.6
The Access Preparation
The access preparation should give visibility and
easy access to the root canals and also allow a
complete eradication of residues of pulp tissue
and microorganisms. At the same time care
should be taken to save tooth substance.
A number of different access burs are available that have in common to cut the surface effectively with as little damage to the tooth and
resaturation as possible. Before starting drilling
through a crown, its outline and its position in
relation to the root must be examined and
considered. For e­xample, the root might be
­
rotated but the crown is placed in line with the
tooth arch.
The access cavity needs to be large enough
to give the operator a possibility to see and
introduce the instruments into root canal with
a “straight-line access”. Rotary or reciprocating instruments should be allowed to act freely
without touching the cavity walls. If touching
the cavity walls during instrumentation the
tapered instruments will be transported within
the root canal, and there will be a risk of creating a ledge or instrument fracture. The judicious clinician also considers to reduce cusps
not only for good access but also to avoid fracture of undermined tooth substance. The most
commonly needed cusps to be reduced are the
mesiobuccal on the upper molar and the buccal on the lower molar.
8.7
ubber Dam and Aseptic
R
Working Field
Next a rubber dam is placed to seal off the tooth
and to create an operating field with good aseptic properties. The rubber dam will render an
obstacle for saliva and microbes to enter into
the cavity and thereby give the operating dentist
a possibility to concentrate on eradicating the
root filling material and microorganisms within
the root canal [14]. This basic endodontic practice also enhances a good field of view and
93
comfort both for the patient and the operator.
Furthermore patient safety considerations
require the use of rubber dam in order to prevent inhalation or ingestion. The isolated tooth
and the clamp and rubber dam fabric that surrounds it should preferably be also be disinfected in order to further minimize risk of
contamination during the treatment. For example, Möller suggests that the tooth is firstly
cleaned with 30% hydrogen peroxide and then
after disinfected with 10% iodine tincture [15].
8.8
emoving the Root Filling
R
Material
The aim is to remove the root filling material
together with necrotic pulp material and/or
embedded microorganisms in order to create
access to and enable a chemomechanical debridement of the persisting biofilm. At the same time
the clinician must be prudent not to remove an
excess of root dentine that in turn can jeopardize
tooth survival in the long term. Depending on the
type and quality of the root filling, it will be differences in difficulty and time for its removal. A
tooth that has been root filled with sealer and has
had excessive amount of leakage into the root
canal will be more easy to treat than a tooth root
filled with a densely compacted gutta-percha and
a hard-set sealer or one filled with a core material
such Thermafil™ or similar. It is a good clinical
practice to probe the root-filled canal with a file,
preferably a K-file 15, to feel to what extent it is
possible to bring the file down in to the root filling material. This will give an immediate indication on the quality of the seal. If the quality is
poor, the instrument will with ease penetrate into
the root canal.
8.8.1
Removing Gutta-Percha
and Sealer
The root filling removal is preferably done using
a stepwise “crown-down” strategy. It is strongly
C. Ulin
94
recommended not to push or advance any rotary
instrument (burs, drills or root canal instruments)
beyond the length that has been first accessed by
a K-file 15 (corresponding to creating a “glide
path” in primary treatments).
A low-speed bur can be used to remove the
1–2 mm coronal part. In the next step, Gates
Glidden drills can be used to advance further
3–5 mm down the root canal. Rotary or reciprocating instruments may now be the perfect
choice to start to create a predetermined shape
of the root canal [16]. The file should be working in the centre of the material to avoid iatrogenic damages. Many of the rotary file systems
have special retreatment files that are usually
stiffer and with non-cutting tip and also design
to be driven at a higher speed. However the procedure must be done with caution because of
the risk creating a ledge. By careful widening
of the coronal part of the root canal, a better
access to the apical part is created. Hand files,
preferably Hedstrom files, can be used but will
be more time consuming. Studies have shown
that rotary files remove root filling material and
prepare the root canal more quickly comparing
to hand-instrumentation. Rotary files will leave
more root filling materials behind inside the
root canal compared to hand files [17, 18].
Using rotary files often needs finishing off with
hand files to remove the middle and apical part
of the remaining gutta-percha. Ultrasonic files
may also be used for this purpose. Remnants of
sealer and cement are also easier removed by
ultrasonic without risk of removing more root
canal dentine.
8.8.2
Removing Plastic Carriers
Carriers covered by gutta-percha are easiest
removed by creating a space between the
material and root canal wall by inserting a
rotary file. The operator must be aware of the
risk that the pressure of the wall will control
the movements of the file and consequently
use only light pressure in order to avoid creating a ledge or even perforation if canal is
curved.
8.8.3
Solvents
Solvents of gutta-percha and some sealers may
be a valuable adjunct in the retreatment procedure when the root canal is densely packed or if
the root-filled canals are severely curved.
Guttasolv™, Endosolv™ and chloroform are
substances aimed for this purpose. Entering a few
drops of the solvent into the canal will soften the
gutta-percha, and the file can lodge in to the
material and follow its path. Since many of these
solvents contain chemicals potentially allergenic
or even carcinogenic, they should be considered a
working environmental hazard. The solvent also
creates a layer of gutta-percha on the root canal
walls that can be difficult to remove. Therefore
they should be used with caution and only when
considered necessary and not on a routine basis.
8.9
Instrumentation
of the Apical Part
When the previous root filling has been successfully removed the root canal instrumentation, I
made the same way as at a primary treatment.
The rotary or reciprocating instrument sequence
should be followed and working length measured
as recommended by the manufacturers. A conceivable crown-root length is estimated by studying the preoperative x-rays. An apex locator is
preferably used together with an intraoral x-ray.
Since the natural taper and possibly the constriction of the root canal is damaged by previous
instrumentations, the apex locator will most
likely only show if inside or outside of the root
canal and not if the constriction is approaching as
normally is shown. The intraoral x-ray will add
information about the position and direction of
the file in the root canal. It will also give an idea
8
Non-surgical Retreatment
of the amount of root filling material still remaining. After working length determination, the root
canal preparation continues accordingly to the
manual of the selected system and with adjustments selected by the clinician for the individual
case. Preferably the apical dimension is above
ISO 20 to enable an effective removal of the
microorganisms to working length [19, 20]. If the
apical dimension needs to be enlarged, be aware
of that further enlargement gives higher risk of
perforation, zipping or transportation of the root
canal. Overinstrumentation has a negative impact
on the prognosis of endodontic retreatment and
should always be avoided [1].
8.10
bstacles and Previous
O
Mishaps
8.10.1 Ledges
Often a ledge has been formed at the end of the
previous filling in the coronal, middle or apical
part of the root canal. Often the ledge is the
result of an inadequate angle of access to the
root canal during primary treatment. The ledge
can be passed and removed if access to the root
canal can be recreated. But, it may be very difficult or even impossible to pass a ledge.
However, the attempt should commence with a
pre-flaring of the coronal portion of the canal
giving the operator a chance to move the file in
the right direction. Usually the coronal part of
the canal needs to be widened even more but in
the opposite way of ledge. A K-10 file pre-bent
in its apical portion can be used to probe the
actual pathway. First, the file should be inserted
in the canal with the tip directed toward the
canal curvature. With very short strokes, the
clinician must search for a catch. If unsuccessful, the file tip must be bended in a slightly
other way and the procedure is repeated until a
catch is felt. Then the file should be wiggled
back and forth maintaining a light apical pressure. By moving the file in an up-and-­down
95
motion, the ledge is smoothed. A Hedstrom file
size 15–20 can also cautiously be used to establish a good glide path. When the block is
bypassed, copious sodium hypochlorite irrigation should be used to remove debris.
8.10.2 Instrument Fractures
During the primary treatment, a root canal instrument may have been fractured and left inside the
root canal. Instrument fracture occurs and it is
mostly due to a procedural error. The frequency
of instrument fracture during root canal treatment
has been reported to be 1–5% [21]. In retreatment
cases the root filling material can act as a blockage of the file that will then not rotate freely and
as a consequence instrument fracture may also
occur during retreatment procedures. Removal of
fractured instruments can be difficult and is
depending on the location within the canal. If in
the coronal part before the apical curvature, the
instrument is more likely to be managed and
removed. The fractures occurring in the coronal
part are often due to excessive amount of apical
pressure, and if in the apical curvature, cyclic
fatigue is more likely to be the reason. Since the
file has been rotated and screwed inside the root
canal wall or root filling material, the principle is
that it has to be rotated out. The possibility to
access the coronal 1–2 mm of the broken instrument needs to be assessed without major risk of
root perforation. A careful monitored preoperative radiographic examination is therefore mandatory. The access is made preferably by a blunt
instrument such as a bevelled Gates Glidden drill
which will create space for an ultrasonic thin tip
to reach in between the file and the root canal
wall. The ultrasonic tip is rotated around the broken instrument in a counterclockwise direction
removing small amounts of dentine and vibrating
the file until it comes loose. The procedure can be
very time consuming, and the necessity of its
removal and cost-benefit is to be considered [22]
(Fig. 8.3).
C. Ulin
96
a
b
c
d
Fig. 8.3 (a) Tooth 34 is diagnosed with a fractured
instrument that is judged to be removable without major
tooth loss. (b) The instrument was removed by using a
thin ultrasonic tip in an anticlockwise motion. (c) Case
completed with a root filling. (d) Tooth 36 with an instrument fracture. Excessive removal of dentine and the risk
of root perforation that are evident in the attempt to
remove the instrument are obvious
8
Non-surgical Retreatment
97
The perforation can be sealed off by using different
material that has hydrophilic properties in common.
MTA (mineral trioxide aggregate) and similar bioceramic materials have shown good characteristics
for this purpose [24]. The sustainability over time is
not known. To be able to seal the perforation, observation and access is necessary and can be created by
good magnification and illumination. Another consideration that needs to be taken into account is the
possibility to find the root canal in the perforated
area and the ability to successfully treat the root
canal after the perforation has been sealed off.
Fig. 8.4 A Stropko™ irrigation needle inserted in the
mesial-buccal root canal of 36 to working length
8.10.3 Perforations
Root canal perforations may be present in all
parts of the root canal system as a consequence of
mishaps during root canal therapy, post space
preparation or as a result of the extension of an
internal resorptive defect. A perforation that is
diagnosed during retreatment procedures has to
be analysed from different aspects. The location,
the size and the time that has elapsed since its
occurrence seem to be the most important issues
in order to make a decision whether to carry on
the treatment or not.
The prevailing view is that coronal perforations
have the worse prognosis [23]. At the coronal level
the inflammatory process that develops as a
response to the perforation might easily communicate with the gingival pocket and establish a periodontal defect. It is therefore favourable to seal any
perforation site at an early stage. A wide perforation
will be more difficult to seal than a small one. Nonsurgical repair is less affected by the location of the
perforation than a surgical approach to treatment,
which can be impossible in certain areas of the root.
The perforation also creates difficulty in
good asepsis during treatment whereby it has
to be controlled. The perforation can occur
during the access preparation and the root
canal ­instrumentation creating different size
and access to the perforated area.
Through the years numerous techniques and
materials to repair perforations have been described.
8.10.4 Overinstrumentation
Overinstrumentation is a type of perforation that
occurs at the site or in close proximity to the apical foramen. It has a negative impact on the prognosis of any endodontic treatment and should be
avoided. The natural constriction of the root
canal is damaged, and the natural stop for the root
canal preparation and root filling is injured. It
creates a possibility for exudate from the periapical area to enter the root canal system, feeding
any remaining microorganisms with nutrients
and at the same time allowing their waste products to evade into the periapical area and sustain
apical pathology.
Overinstrumentation can be avoided by using
an apex locator and working length x-rays to
hereby control the position of the file within the
canal. Apex locators are probably better than
x-rays to establish working length [25, 26].
8.11
Chemical Disinfection
8.11.1 Irrigation
The cultivable microbiological flora within a filled
root canal with apical periodontitis is different
comparing the non-root-filled canal. The strains are
fewer and the facultative anaerobes are predominant [27]. The microbes are situated on the root filling material, between the gutta-percha and root
canal wall as well as within the dentinal tubules, as
shown by Nair et al. [28, 29]. The mechanical
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98
removal of the infected root filling material is made
by different instruments which will give access to
the dentine. The microbes are colonizing the sites
in form of a biofilm that helps them to protect
themselves from any attempts to kill them by the
use of chemicals. Consequently, the instrumentation and irrigation preferably should, as far as possible, disrupt the biofilm in order to make the
microbes more susceptible for the antiseptic effect
of the irrigant. Tissue-­dissolving features are therefore an essential requirement. The irrigant should
also be able to reach areas that cannot possibly be
touched by the instruments. Therefore low surface
tension is an important property.
The disinfection irrigant should be able to
kill or at least permanently inactivate the microbiota within the root canal system. At the same
time the agent has to be minimally toxic and not
cause tissue damage if accidentally entering
beyond the root canal system. Depending on the
irrigation device used, the solution is, more or
less, able to reach to the working length without
penetrating out in to the periapical area.
None of the currently used agents is fully satisfying the above requirements.
8.11.1.1
Sodium Hypochlorite
(NaOCl)
Sodium hypochlorite has the ability to disrupt the
microbiological biofilm within the root-canal and
is a potential antiseptic agent. It has been extensively used within endodontics and has good evidence to be effective both in vitro and in clinical
studies [30]. Sodium hypochlorite is the main
irrigant of choice. Which concentration should be
used is up for further investigation. Higher concentration will increase the risk of severe toxic
effects if sodium hypochlorite is flushed through
the root apex. The treatment time will increase
with lower concentration but it can be safer [31].
Lower pH and higher temperature change sodium
hypochlorite to become more effective at lower
concentrations [32]. The optimal concentration,
pH and temperature are to be investigated.
Sodium hypochlorite is quickly inactivated by
the presence of oxidizable material such as dentine debris and organic material [33]. Therefore it
has to be replenished consistently.
8.11.1.2 EDTA
Ethylenediaminetetraacetic acid binds calcium
and is used to remove the created smear layer
while instrumenting the root canal. Removing the
smear layer will create access for other irrigants
to the root dentine. The smear layer often contains bacterial residue which preferably is eradicated [34].
8.11.1.3
hlorhexidine and Iodine-­
C
Potassium Iodide
The understanding of the infected root canal and
the complexity of the biofilm have increased over
the last decades. The fact that particularly resistant microorganisms have been found in root-­
filled teeth has enabled clinicians and researchers
to try using alternative or complementary irrigation fluids either to more effectively remove
microbes initially or to enhance chemical disinfection in retreatment, disinfectants that can be
more effective to yeast and enterococcus than
NaOCl [35].
Chlorhexidine is used due its biocompatible
and binding properties to hydroxyapatite. Two
percent chlorhexidine gluconate is used, but its
lack of tissue-dissolving properties makes it not
useful as a sole irrigant but in conjunction with
NaOCl. Mixing NaOCl with chlorhexidine will
give para-chloroaniline as a precipitate. This
pink-coloured residue might cover the root canal
wall and prohibit the effect of NaOCl. The efficacy of iodine-potassium iodide particularly targeted against species of Enterococcus has found
some support both in vitro and clinical protocols
[35, 36]. Iodine-potassium iodide may be used
preferably after EDTA.
8.11.1.4 Irrigation Methods
Irrigating the root canal with a syringe and a needle is the most common technique. Needles of
different designs and material are available. The
scope is to find a technique that reaches the whole
space of the root canal and preferably its surrounding crevices, bi-canals and isthmuses. At
the same time the irrigating method used should
also prevent the irrigation solution to penetrate
the root canal foramen, thereby risking damage
to surrounding tissue.
8
Non-surgical Retreatment
Gulabivala et al. [37] describe the fluid mechanism of root canal irrigation where a greater taper and
a side-vented needle design will render the s­ afest and
best effect. Needle material of Ni-Ti will give the
device a possibility to follow the curvature of the root
canal and to reach the apical area (Fig. 8.4).
The activation of the irrigation solution by an
ultrasonic device will give agitation of the fluid
and create a higher possibility of tissue dissolving and a disruption of the biofilm within the root
canal [38].
8.12
Inter-appointment Dressings
8.12.1 Calcium Hydroxide
Calcium hydroxide in aqueous solution is a
strong alkaline solution with a pH of 12.5. It dissociates into calcium and hydroxyl ions, of which
the later have strong antimicrobial effect when
into direct contact with the microflora. The
tissue-­dissolving effect of the hydroxyl ions is
also helpful in the disruption of the biofilm.
A classical study by Sjögren et al. [2] has
shown that inter-appointment dressing with calcium hydroxide reduces the amount of microflora
within the root canal, although the antiseptic effect
of calcium hydroxide on facultative anaerobes
such as Enterococcus faecalis and yeast, for example, Candida albicans, has been questioned [39].
However, in a retreatment case when treatment often is complicated and time consuming
and therefore split into more than one session, it
seems advantageous to use calcium hydroxide to
prohibit growth of bacteria in the root canal
between visits. By filling the root canal with calcium hydroxide, the nutritional supply to
microbes by inflammatory exudates from the
periapical area is blocked.
8.13
Root Filling
The procedure of placing a new root filling may
be as challenging as removing the old one.
Often, the anatomy of the root canal has been
transformed due to the treatment, and it is no
99
longer of a form that co-inherit with the guttapercha points manufactured to fit to a particular
file system. The apical size will often be larger
and the taper greater. The root filling technique
to be used needs to encounter these properties.
There is no evidence to suggest that any particular method or material systematically results in
better outcome than any other. However, the
variety of situations challenges the clinician to
adapt his or her technology to the various conditions prevailing in each individual case. The key
to achievement is usually to first of all fill the
apical part and as a second step fill the coronal
part of the root canal. The apical part is preferably filled with a master point that correlates, as
well as possible, to the shape of the canal in this
apical 4–5 mm from the working length and the
rest of the root canal with a warm gutta-percha
technique. If the root canal has been retreated
and enlarged to a shape that co-inherits with a
particular instrument in a particular instrumentation system, the canal is easiest filled with the
corresponding gutta-percha.
It has been shown that a root filling with a thin
layer of sealer gives the best properties when it
comes to leakage [40, 41].
After the root filling it is sometime advocated
to place a bacterial-tight filling 2–3 mm in the
coronal part of the root canal. This is to prevent
coronal leakage. There are no clinical studies to
support this recommendation [42]. Also, Ricucci
et al. [43] could show that teeth that had been
optimally endodontically treated and showed
good-quality root fillings did not show apical
pathologies when exposed to the oral cavity for a
long period of time.
After the root filling is made, the resaturation of
the coronal part is due to take place. The possibility
of a good coronal resaturation after the endodontic
treatment should always be taken into consideration when doing the treatment planning.
8.14
Follow-Up
One of the best ways to know if your strategy has
been successful is to do your own follow-ups.
You thereby learn what challenges you have to
C. Ulin
100
overcome and what you have to consider when
treatment planning is made. However the follow-­
ups must be made systematically and over a longer period of time in order not to jump into
conclusions or let rare individual events distort
the overall results.
Follow-up of endodontic treatment takes time.
The way of knowing if a treatment of an apical
periodontitis has been successful is to follow the
size of the periapical destruction on an x-ray. The
time between treatment and follow-up needs to
be as long as periapical changes are likely to be
seen. A first follow-up time of 12 months is
therefore often recommended. The follow-up
includes an anamnestic report of subjective and
objective symptoms and x-rays. The x-rays
should mimic the preoperative x-rays which
gives the best opportunity to follow changes in
the periapical area (Fig. 8.5). Strindberg in his
thesis from 1956 [44] could show that the most of
the periapical lesions that where less in size after
1 year usually had healed after 4 years. However,
to be able to confirm complete healing, it requires
follow-up periods that sometimes need to be
extended to the length of an entire professional
career (Fristad et al. [45]).
a
Take-Home Lessons
• Diagnosis, case selection and treatment
planning are the keys for successful outcome of non-surgical retreatment.
• When retreating a root canal, the downside is that you are bound to someone
else’s pathway within the root canal.
• Create a treatment strategy and an
objective for the procedures, and make
sure to apprise your patient and get his
or her informed consent.
• Consider the challenges in removing the
root filling material and the more robust
microbial flora in advance.
• Do follow-ups to learn and to create an
individual evidence-based database.
Benchmark Papers
• Bergenholtz G, Lekholm U, Milthon R,
Heden G, Ödesjö B, Engström B.
Retreatment of endodontic fillings. Scand
J Dent Res. 1979;87:217–24.
b
Fig. 8.5 (a) Preoperative x-ray with clearly visible apical lesions. (b) 12-month follow-up after retreatment, periradicular tissues exhibit clear signs of a bone healing process
8
Non-surgical Retreatment
• Ng YL, Mann V, Gulabivala K. A prospective study of the factors affecting
outcome of nonsurgical root canal treatment: part 1: periapical health. Int
Endod J. 2011;44:583–609.
• Molander A, Reit C, Dahlén G, Kvist T.
Microbiological status of root-filled
teeth with apical periodontitis. Int
Endod J. 1998;31:1–7.
• Nair PN, Sjögren U, Krey G, Kahnberg
KE, Sundqvist G. Intraradicular bacteria
and fungi in root-filled, asymptomatic
human teeth with therapy-resistant periapical lesions: a long-term light and
electron microscopic follow-up study. J
Endod. 1990;16:580–8.
The studies show that the prognosis of
root-filled teeth and its treatment are
dependent on the quality of the previous
made endodontic treatment. The influence
of procedural errors and lack of microbial
eradication are factors to be considered
and also to be able to control while performing non-surgically retreatment.
References
1. Bergenholtz G, Lekholm U, Milthon R, Heden G,
Ödesjö B, Engström B. Retreatment of endodontic
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2. Sjögren U, Hägglund B, Sundquist G, Wing K. Factors
affecting the long-term results of endodontic treatment. J Endod. 1990;16:498–504.
3. Ng YL, Mann V, Gulabivala K. A prospective study
of the factors affecting outcome of nonsurgical root
canal treatment: part 1: periapical health. Int Endod
J. 2011;44:583–609.
4. Swedish Council on Health Technology Assessment.
Methods of diagnosis and treatment in endodontics—
a systematic review. Report no. 203; 2010. p. 1–491.
http://www.sbu.se.
5. European Society of Endodontology, Patel S, Durack
C, Abella F, Roig M, Shemesh H, Lambrechts P,
Lemberg K. European Society of Endodontology
position statement: the use of CBCT in endodontics.
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11. Main C, Mirzayan N, Shabahang S, Torabinejad
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aggregate: a long-term study. J Endod. 2004;30:80–3.
12. Krupp C, Bargholz C, Brüsehaber M, Hülsmann
M. Treatment outcome after repair of root perforations with mineral trioxide aggregate: a retrospective
evaluation of 90 teeth. J Endod. 2013;39:1364–8.
13. Schwandt NW, Gound TG. Resorcinol-formaldehyde
resin “Russian red” endodontic therapy. J Endod.
2003;29:435–7.
14. Lin PY, Huang SH, Chang HJ, Chi LY. The effect
of rubber dam usage on the survival rate of teeth
receiving initial root canal treatment: a nationwide
population-­based study. J Endod. 2014;40:1733–7.
15. Möller ÅJR Microbiological examination if root
canals and periapical tissues of human teeth. Scand
Dent J. 1966;74(5 and 6).
16. Molander A, Caplan D, Bergenholtz G, Reit C. Improved
quality of root fillings provided by general dental practitioners educated in nickel-titanium rotary instrumentation. Int Endod J. 2007;40:254–60.
17. Betti LV, Bramante CM. Quantec SC rotary instruments versus hand files for gutta-percha removal in
root canal retreatment. Int Endod J. 2001;34:514–9.
18. Bernardes RA, Duarte MA, Vivan RR, Alcalde MP,
Vasconcelos BC, Bramante CM. Comparison of three
retreatment techniques with ultrasonic activation in
flattened canals using micro-computed tomography
and scanning electron microscopy. Int Endod J. 2015;
https://doi.org/10.1111/iej.12522. Epub ahead of print.
19. Huang TY, Gulabivala K, Ng YL. A bio-molecular
film ex-vivo model to evaluate the influence of canal
dimensions and irrigation variables on the efficacy of
irrigation. Int Endod J. 2008;41:60–71.
20. Clars Dalton B, Örstavik D, Philips C, Petiette M,
Trope M. Bacterial reduction with nickel-titanium
rotary instrumentation. J Endod. 1998;11:763–7.
21. Shen Y, Coil JM, McLean AG, Hemerling DL,
Haapasalo M. Defects in nickel-titanium instruments
after clinical use. Part 5: single use from endodontic
specialty practices. J Endod. 2009;10:1363–7.
22. Suter B, Lussi A, Sequeira P. Probability of removing fractured instruments from root canals. Int Endod
J. 2005;38:112–23.
23. Petersson K, Hasselgren G, Tronstad L. Endodontic
treatment of experimental root perforations in dog
teeth. Endod Dent Traumatol. 1985;1:22–8.
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24. Guneser MB, Akbulut MB, Eldeniz AU. Effect of
various endodontic irrigants on the push-out bond
strength of biodentine and conventional root perforation repair materials. J Endod. 2013;39:380–4.
25. Ravanshad S, Adl A, Anvar J. Effect of working length measurement by electronic apex locator or radiography on the adequacy of final working
length: a randomized clinical trial. J Endod. 2010;36:
1753–6.
26. Williams CB, Joyce AP, Roberts S. A comparison
between in vivo radiographic working length determination and measurement after extraction. J Endod.
2006;32(7):624.
27. Molander A, Reit C, Dahlén G, Kvist
T. Microbiological status of root-filled teeth with apical periodontitis. Int Endod J. 1998;31:1–7.
28. Nair PN, Sjögren U, Figdor D, Sundqvist G. Persistent
periapical radiolucencies of root-filled human teeth,
failed endodontic treatments, and periapical scars.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod.
1999;87:617–27.
29. Nair PN, Sjögren U, Krey G, Kahnberg KE, Sundqvist
G. Intraradicular bacteria and fungi in root-filled,
asymptomatic human teeth with therapy-resistant periapical lesions: a long-term light and electron microscopic follow-up study. J Endod. 1990;16:580–8.
30. Zendher M. Root canal irrigants. J Endod. 2006;32:
389–98.
31. Bystrom A, Sundqvist G. The antibacterial action of
sodium hypochlorite and EDTA in 60 cases of endodontic therapy. Int Endod J. 1985;18:35–40.
32. Moorer WR, Wesselink PR. Factors promoting the
tissue dissolving capability of sodium hypochlorite.
Int Endod J. 1982;15:187–96.
33. Haapasalo HK, Sirén EK, Waltimo TM, Örstavik D,
Haapsalo MP. Inactivation of local root canal medicaments by dentine: an in vitro study. Int Endod
J. 2000;33:126–3.
34. Sen BH, Wesselink PR, Türkün M. The smear layer:
a phenomenon in root canal therapy. Int Endod
J. 1995;28:141–8.
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35. Portenier I, Haapasalo H, Orstavik D, Yamauchi M,
Haapasalo M. Inactivation of the antibacterial activity
of iodine potassium iodide and chlorhexidine digluconate against Enterococcus faecalis by dentin, dentin matrix, type-I collagen, and heat-killed microbial
whole cells. J Endod. 2002;28:634–7.
36. Peciuliene V, Reynaud AH, Balciuniene I, Haapasalo
M. Isolation of yeasts and enteric bacteria in root-­
filled teeth with chronic apical periodontitis. Int
Endod J. 2001;34:429–34.
37. Gulabivala K, Ng YL, Gilbertson M, Eames I. The
fluid mechanics of root canal irrigation. Physiol Meas.
2010;31:49–84.
38. Stojicic S, Zivkovic S, Qian W, Zhang H, Haapasalo
M. Tissue dissolution by sodium hypochlorite: effect
of concentration, temperature, agitation, and surfactant. J Endod. 2010;36:1558–62.
39. Vianna ME, Gomes BP, Sena NT, Zaia AA, Ferraz
CC, de Souza Filho FJ. In vitro evaluation of the
susceptibility of endodontic pathogens to calcium
hydroxide combined with different vehicles. Braz
Dent J. 2005;16:175–80.
40. De-Deus G, Coutinho-Filho T, Reis C, Murad C,
Paciornik S. Polymicrobial leakage of four root
canal sealers at two different thicknesses. J Endod.
2006;32:998–1001.
41. Wu MK, Wesselink PR, Boersma J. A 1-year follow­up study on leakage of four root canal sealers at different thicknesses. Int Endod J. 1995;28:185–9.
42. Yamauchi S, Shipper G, Buttke T, Yamauchi M, Trope
M. Effect of orifice plugs on periapical inflammation
in dogs. J Endod. 2006;32(6):524.
43. Ricucci D, Gröndahl K, Bergenholtz G. Periapical status
of root filled teeth exposed to the oral environment by
loss of restorations or caries. Oral Surg. 2000;90:354–9.
44. Strindberg LZ. The dependence of the result of pulp
therapy on certain factors. Acta Odontol Scand.
1956;14(Suppl 21):1–175.
45. Fristad I, Molven O, Halse A. Nonsurgically
retreated root filled teeth. Radiographic findings after
20–27 years. Int Endod J. 2004;37(1):12–8.
9
Prognosis
Thomas Kvist
Evidence based practice must be based on practice based evidence.
—Inspired by Sackett et al.
in “Evidence based medicine—What it is—and what it isn’t.” 1996
Comparative experience is a prerequisite for experimental and scientific medicine,
otherwise the physician may walk at random and become the sport of a thousand
illusions.
Claude Bernard—“Introduction a l’étude de la medicine expérimentale.” 1866
Abstract
For any human ailment, outcome assessment is a major step. In this chapter the prognosis of persistent apical periodontitis in root-filled teeth is
discussed. However, the focus is on critically examining the evidence concerning this condition and giving a brief overview of the challenges the
discipline of endodontics is facing for future clinical research in order to
close some of the essential “knowledge gaps” regarding apical periodontitis in root-filled teeth.
9.1
Introduction
When people are diagnosed with a disorder, they
have many questions about how this will affect
them in the future. This also holds true for apical
periodontitis in root-filled teeth. And perhaps this
diagnosis will generate extra many anxieties
since the condition is preceded by a previous
treatment attempt that has somehow “failed” in
achieving one or two of the fundamental objectives of root canal treatment. Some frequently
T. Kvist, DDS, PhD
Department of Endodontology, Institute of
Odontology, The Sahlgrenska Academy,
University of Gothenburg, Göteborg, Sweden
e-mail: kvist@odontologi.gu.se
© Springer International Publishing AG 2018
T. Kvist (ed.), Apical Periodontitis in Root-Filled Teeth,
https://doi.org/10.1007/978-3-319-57250-5_9
asked questions concerned with the future of a
persistent apical periodontitis in root-filled teeth
are likely to be as follows:
• How does this problem affect my risk of loosening the tooth?
• Will it affect my general health?
• What different options do I have?
• How likely is it that retreatment will cure the
tooth?
• Would it be a better idea to take the tooth out?
• If so, can it and should it be replaced?
What information should the dentist provide
and should any information be withheld from the
patient? This issue is more deeply discussed in
Chap. 6: Decision making. This chapter will critically discuss the present evidence base for the
103
T. Kvist
104
information we need to be able to convey to our
patients in the situation of facing a root-filled
tooth with persistent apical periodontitis.
9.2
linical Research: The Basis
C
of Statements
About Prognosis
9.2.1
Methods for Clinical Research
Assessment prognosis can be carried out in a
number of ways. Evidence-based medicine/dentistry seeks to prioritize information in a hierarchy of evidence by study design from the most
biassed to the least biassed. Knowledge about
the biology of disease, in vitro studies and studies in models, cadavers or animals are certainly
valuable to the discipline in many aspects. Yet
this kind of research, even if skilfully performed, will very sparsely, if at all, contribute to
evidence-­
based answers to clinical questions.
Because of the complex biology of human
beings, the variation among individuals, the
influence of chance and the interaction between
doctors and patients, valid answers to the clinical questions, must be searched for in clinical
research (Fig. 9.1).
Meta-analyses of RCTS.
Le
Randomized controlled trials.
Prospective cohort studies.
Case-control studies.
w
Case series.
Lo
Fig. 9.1 The “evidence
pyramid” illustrates how
different types of studies
basically are assessed
for their potential ability
to provide different
levels of scientific
evidence for a specific
clinical question
ve
lo
fe
vi
d
en
ce
Hi
gh
Prognosis is a prediction of the future course of a
condition following its onset with or without
treatment. Studies on prognosis should tackle
and give solid answers to clinical questions. A
group of patients with a condition such as apical
periodontitis in a root-filled tooth or a particular
treatment in common, such as endodontic retreatment, are identified and followed forward in time.
Clinical outcomes are measured. Often, conditions that are associated with a given outcome,
i.e. prognostic factors, are sought. The prognosis
of a disease without interference is termed the
natural history of disease. The term clinical
course has been used to describe the evolution
(prognosis) of disease that has come under medical or dental care and treated in a variety of ways
that might affect the subsequent course of events.
It is a difficult but indispensable task to make
clinical research on these issues. The studies may
be affected by biasses that have to be controlled
as far as possible. The objective is to predict the
future of individual patients and their affected
teeth as closely as possible. The intention in the
clinical setting is to avoid stating needlessly
vague prognoses and answer with confidence
when it is deceiving. Therefore, studies aiming to
answer the clinical questions must be scrutinized
for quality [1, 2].
Case reports.
Studies in models and in animals.
9
Prognosis
9.2.1.1 Case Reports
A simple way of clinical research is the description of clinical cases, which may show unique or
unusual features of the condition or outcome of
therapy. Such case analyses are quite common in
endodontic journals and at congresses. It is the
only mean by which specific or even unexpected
clinical events can be described and are therefore
important as further examinations may be initiated. The limitation of case presentations is obvious. Information from a single case cannot be
transferred to other patients because of the wide
variation and many factors not controlled or
checked for.
9.2.1.2 Case Series
Series of cases provide better information.
Larger groups of patients with a particular disease or condition subjected to treatment are studied. The involvement of chance can be checked
by statistical analysis. Yet, the efficiency of the
clinical procedure cannot be ascertained to be
better or equal to any other method if no control
group is available. Sometimes, inclusion of data
from prior studies or other authors’ results is
used for comparison purposes. However, this
procedure will not bring particular strong evidence to the report, as the conditions, under
which the studies were conducted, may not have
been very similar.
9.2.1.3 Case-Control Studies
Case-control studies also belong to the arsenal of
methods of observational studies available for
clinical research. A case-control study assesses
persons with a condition (or another outcome
variable) of interest and a suitable control group
of persons without the condition (comparison
group, reference group). The potential relationship of a suspected risk factor or an attribute to
the condition is examined by comparing the
affected and non-affected subjects with regard to
how frequently the factor or attribute is present
(or, if quantitative, the levels of the attribute) in
105
each of the groups. For an example Kim et al. [3]
studied the influence of a presence of an isthmus
area when performing endodontic surgery in
maxillary and mandibular first molars. Of the 106
teeth, 72 teeth had an isthmus, and 34 did not.
The analysis revealed that the cumulative 4 years
survival rate after surgery was 61.5 and 87.4%,
respectively, when an isthmus was present and
absent.
9.2.1.4 Prospective Cohort Studies
Retrospective studies of any nature will not do
well as they suffer the risk of having limited or no
control of a number of aspects relevant to outcome. To provide good evidence, clinical research
requires being prospective. A type of clinical
research design that has gained increased attention in recent years is the prospective cohort
observational study [4]. Cohort refers to a group
of patients. This study design implies that a large
sample of patients can be treated and then be
assembled for follow-up examinations. An
important factor of such studies is that a fairly
large number of clinics have to be included in
order for the report to gain generalizability. Yet
the study design has the advantage to allow inclusion of general dentists and therefore will give
availability to aspects on endodontics at which
we have very little understanding.
Database-Based Studies
Given that a comprehensive registry of patients
under treatment currently is under way in many
countries, valuable basic information on the efficiency of procedures can be gained [5]. However,
since validated data on diagnoses, treatment protocols and other essential details often are lacking, this type of study cannot give answers to
more detailed clinical questions.
9.2.1.5 Randomized Controlled Trial
Randomized controlled trials (RCTs) are genuine clinical experiments. Two or more groups of
subjects receive different measures, are followed
T. Kvist
106
forward in time and are compared using an outcome assessment. The distinguishing feature of
an RCT is that patients are allocated to test and
control procedures in a strictly randomized manner. This kind of study usually observes the effect
of a single variable only. All other variables (background variables, confounders) are controlled by
the chance effect in both the test and the control
group. To be appropriate RCT requires further a
precalculated minimal number of patients to be
included in order to ensure that a statistical significant difference between the test and the control procedure can be ascertained. RCTs are
indeed powerful tools as many of the biasses that
affect nonrandomized trials can be eliminated.
In Fig. 9.2 the set-up of three different RCTs
is sketched. From a scientific perspective, these
would be highly desirable to implement in order
to provide significantly better knowledge of the
prognosis for apical periodontitis in root-filled
teeth.
a
Yet, the long time they require to conduct
and the high costs make RCTs difficult to perform. On a careful consideration, we must realize that RCTs may not attain evidence-based
research very easily for important clinical
questions for endodontic retreatment. In fact,
RCTs are ideal for testing the effects of drugs
because it can use placebo and be controlled
double blinded. However, for assessment of
important aspects of surgical interventions,
such as endodontic retreatment procedures,
several predicaments occur. For example, it
would probably be difficult to enrol a sufficient
number of root-filled teeth with apical periodontitis similar enough to be randomized to
extraction and implant or non-surgical retreatment. But even if possible, it is likely that the
values and expectations of the patients, the
dentists and the evaluators could influence the
assessment of the outcome since neither
patients, dentists nor evaluators can be blinded
Treatment procedure:
surgical retreatment
Healed
+
TX
All patients with
the condition of
interest:
root filled tooth
and apical
periodontitis
Sample
-
Not healed
Comparison of outcome of
interest:
healing of apical periodontitis
Randomisation
CTR
+
Control procedure:
non-surgical retreatment
-
Fig. 9.2 Basic designs of three RCTs that should be
highly preferred to be carried out in order to increase the
level of scientific evidence for crucial questions regarding
apical periodontitis in root-filled teeth. (a) Comparing the
outcome of periapical tissues following surgical versus
Healed
Not healed
non-surgical retreatment. (b) Comparing “functional
retention” following surgical retreatment versus extraction and replacement with an implant. (c) Comparing
important outcomes following retreatment versus “no
intervention”
9
Prognosis
107
b
Treatment procedure:
surgical retreatment
+
TX
All patients with
the condition
of interest:
root filled tooth
and apical
periodontitis
Sample
Functional
retention
Loss of tooth
-
Comparison of outcome of
interest:
functional retention
Randomisation
CTR
+
Control procedure:
extraction and
replacement with an
implant
-
Functional
retention
Loss of implant
c
Treatment procedure:
retreatment
TX
All patients with
the condition of
interest:
root filled tooth
and asymptomatic
apical
periodontitis
Comparison of outcomes of
interest:
Sample
•
•
•
•
•
Randomisation
Tooth retention and function
Influence of general health
Pain and discomfort
Progression or healing of lesion
Costs
CTR
Control procedure:
no intervention
Fig. 9.2 (continued)
to the allocated treatment (Fig. 9.2a, b). Another
concern is the long follow-­up time necessary to
a meaningful outcome comparison assessment.
If, for example, surgical or non-surgical intervention is compared to extraction implant
placement in a randomized manner (Fig. 9.2b),
the crucial and interesting comparison is at
hand only after several years [6, 7].
Finally, RCTs for the most central clinical
questions have ethical challenges. For example, perhaps the utmost important and vital
RCT would be to randomly allocate ­individuals
T. Kvist
108
with asymptomatic apical periodontitis in rootfilled teeth to retreatment or monitoring the
condition without intervention (Fig. 9.2c). The
many difficulties involved in investigating the
most relevant clinical questions with an RCT
design have resulted in a limited number of
publications over the years. And most of them
are investigating relatively trivial issues [7] but
still without evidence-based answers even to
these.
are utilized. Meta-analysis is a specialized
type of systematic review, where data are
pooled for a quantitative rather than a qualitative analysis. This type of study can provide
the highest level of evidence, if the report is
limited to proper RCTs. However, a metaanalysis cannot give a higher-quality evidence
than that which exist in the studies included in
the analysis.
9.2.1.6 Systematic Reviews
and Meta-Analyses
There are several approaches to summarize the
scientific basis for clinical practice. In recent
years, when thanks to developments of computer and IT technology, large amounts of data
and literature can be both searched and retrieved
within a very short period of time, so-called systematic reviews have become increasingly common. By definition the review must be conducted
in a systematic way and contain at least four
components:
9.2.2
• Formulation of a clear question (or several
clear questions)
• Searching and identifying relevant research
• Collecting and critically analysing included
reports
• Summarizing results, making conclusions and
giving recommendations as to how to proceed
in the clinical setting
Systematic reviews are a special type of
review article, which can be considered to provide the highest level of evidence when several similar RCTs on the same clinical question
ssessing the Quality
A
of Available Research
In assessing the scientific quality of a clinical
research report, a number of factors are essential.
These aspects sum up into an account of internal
validity (the degree to which the results of a study
are correct for the sample of patients being studied) and the extent of external validity (generalizability) (the degree to which the results of an
observation hold true in other settings).
9.2.2.1 The PICO Concept
A good starting point to use for evaluating the
quality of a RCT is the PICO concept (Fig. 9.3).
It stands for population, intervention, control
procedure and outcome measure. The PICO
model can also be adopted for other types of
studies both for planning and for evaluating individual studies, for example, when pursuing a
systematic review. At each “letter” there are
however many pitfalls that have to be avoided if
the study is to produce results of high internal
and external validity. PICO helps the researcher
or evaluator to systematically evaluate all the
phases of a study.
9
Prognosis
Population (P)
109
Humans
•
Intervention (I)
•
Root filled permanent teeth with asymptomatic apical
periodontitis 4 years after root canal treatment
•
“Healthy” patients
•
No caries or any other indication for further
intervention than persistent apical periodontitis
•
Maximum one tooth/individual
Surgical root canal retreatment
•
Surgical procedure using surgical microscope,
ultrasonic preparation and retro-filling with
MTA
Control (C)
•
Outcome (O)
5 Years after treatment
No intervention
•
General health evaluation
•
Tooth retention and function
•
Patients’ evaluation of pain and discomfort
•
Healing of apical periodontitis
•
Total costs of each option
Fig. 9.3 The PICO concept applied for a RCT on important outcomes following retreatment versus “no intervention”
of root-filled teeth with asymptomatic apical periodontitis
9.2.2.2 Biasses in Clinical Research
“Bias” is the term for a process at any stage of
inference tending to produce results and conclusions that deviate from the true condition systematically. The quality of studies is subject to the
risk of being limited by numerous biasses. The
problem affects all kinds of reports including the
top articles in the evidence pyramid (prospective
cohort studies and RCTs) (Fig. 9.1). Biasses are
in four wide-ranging categories, viz. sampling
bias, selection bias, measurement bias and confounding bias [8].
Sampling Bias
Sampling bias arises when the sample of patients
is systematically different from those suitable for
the research question or the clinical use of the
information. For example, studies on the outcome
of endodontic retreatment have exclusively been
conducted in dental schools or specialist centres.
An important question is if these teeth are representative of “root filled teeth with apical periodontitis” in general? Perhaps the teeth treated are a
sample of “suitable teeth” for referral and treatment [9]. When reporting a clinical study, it is
110
always important to accurately describe the inclusion and exclusion criteria for the subjects included
in the study.
Selection Bias
Selection bias arises when comparisons are
made on groups that differ in ways, other than
the factors under study. Groups of patients often
differ in many ways by age, sex, general health
and severity of disease. If we compare the outcome of two groups that differ on a specific issue
of interest (e.g. surgical versus non-surgical
retreatment) but are dissimilar in any other way
and this difference itself is related to the outcome of interest, the comparison between the
groups will be biassed. Thus, little can be concluded from the results. In our example of surgical versus non-­
surgical retreatment, if “easy
cases with easy access” (perhaps premolars and
incisors) are more frequent in the non-surgical
group, the outcome may be systematically better
or poorer. Randomization is the best way to
overcome these difficulties. The randomization
procedures must then be performed without
manipulation and be clearly described in the
methods of the study.
Measurement Bias
Measurement bias arises, when the means or
methods of measurement are different among the
groups of patients. This is the reason why historical comparisons (data from other reports) often
are invalid. Another problem may be the lack of
common criteria for evaluating the outcome. For
example, when comparing results of non-surgical
and surgical endodontic procedures, there is no
mutually recognized way to interpret “healing
from “no healing” in radiographs. The problem
with intra- and interobserver variation must also
be handled in an appropriate way by using
blinded and independent evaluators.
Confounding Bias
Confounding bias arises when two factors are
associated with each other, and the effect of one
is confused with or distorted by the effect of
another, not measured or controlled, factor. For
T. Kvist
example, if survival of a group of teeth, which
had a surgical retreatment, is compared with a
group where non-surgical retreatment was conducted. Perhaps the result showed a significantly
higher survival after 10 years in the non-­surgical
retreatment group. Yet in further analyses of the
data, it was revealed that in the non-­
surgical
group, a new crown was placed more frequently
postoperatively than in the surgical group.
Consequently, it may be that the placement of the
new crown rather than the choice of treatment
explained the observed difference in outcome.
9.2.2.3 Statistical Analysis
The observed difference between the intervention
and the control group in a clinical study cannot
be expected to represent a true difference because
of the random variation between the groups being
compared. Statistical tests help to estimate how
well the observed difference approximates the
real difference.
There are two main approaches to assess the
role of chance in clinical studies, hypothesis testing and estimation. With hypothesis testing statistical tests are conducted to calculate the
probability that the observed result was by
chance. This calculation may result in both false-­
positive and false-negative statistical errors. The
type I error relates to the conclusion of an effect
of the tested procedure that does not exist in reality, while a type II error means that there is a
positive effect, which data failed to show. The
acceptable size of the risk for errors of both types
is a value judgement. It is customary to set the
risk for type I errors to 1 or 5%. For type II errors,
a considerably higher risk of error is normally
accepted, and the probability is usually given at
20%.
In order to avoid statistical errors, sample
size is an important concern. A calculation
(“power analysis”) should therefore be carried
out prior to the onset of a study to analyse how
many patients should be needed to avoid a type
II error. Generally speaking more patients are
required to detect small differences than if large
differences are in centre of attention. However,
even with a proper “power analysis” and
9
Prognosis
respected in the implementation of the study,
researchers take the risk of being mistaken every
fifth time a study does not show a statistically
significant difference (type II error 20%). If a
statistically significant difference is found, the
risk of being mistaken is, however, only one
(type I error 1%) or five (type I error 5%) in
hundred instances.
These potential errors in hypothesis testing
have made many researchers and statisticians to
prefer estimation statistics [10]. This type of control for chance uses the data to define the range of
values that is likely to include the true effect.
Point estimates (the observed effect) and confidence intervals are used here. They emphasize
the size of the effect and not the p-value and show
the range of plausible values.
9.2.2.4 S
tatistical and Clinical
Significance
It is important to realize that statistical difference
only tells if the difference observed is likely to be
true, but not that it is important or large. In clinical research, it is therefore highly important to
clear the distinction between statistical and clinical significance. Even with a small p-value (the
risk of a type I error), it is not necessary so that
the difference is clinically important. In fact,
completely trivial differences in well-designed
studies may be highly significant on a statistical
level, if a large number of patients were studied,
but the difference may be clinically of little or no
relevance.
9.2.2.5 Loss to Follow-Up
A serious problem in clinical research is the loss
of patients to follow-up. Numerous examples
exist in the endodontic retreatment literature,
where too many patients were unable to attend
the control. Short follow-up periods of 1 and
2 years may do well, but once extended, patient
losses increase, and the results can easily
become invalidated. Thirty per cent is a common figure used in systematic reviews as the
highest loss of patients for recall in a study to be
included in a systematic review. However, while
5 and 10 years follow-up data are highly desir-
111
able, few, if any study, have been published in
the focus area of this book that reach this high
number of attendance at this point postoperatively [7]. Losses of patients may be due to various reasons. A most important, which normally
cannot be checked, is that the treatment failed
and resulted in a decision of the patient not to
attend the recall or to take the tooth out by
another dentist.
9.2.2.6 Clinically Relevant Outcomes
Because of their selection and training, dentists in
general and scholars in particular tend to prefer
the kind of precise measurements the physical and
biologic sciences provide. They discount others
especially for research. Within endodontic retreatment there are numerous studies concerned with
the quality of root fillings and disappearance or
reduction of periapical radiolucencies. Yet, relief
of symptoms, retaining a functional and asymptomatic tooth in the long term and the feeling of
well-being are among the important outcomes of
dental care. These are central concerns of patients
and dentists alike. To guide clinical decisions,
reports of clinical research should therefore focus
on more patient-centred outcomes.
9.2.2.7 Efficacy and Effectiveness
Results of clinical studies must be judged in relation to two broad questions. Can the diagnostic
method or treatment work under ideal circumstances? And does it work in ordinary settings?
The terms efficacy and effectiveness have been
applied here. It may be a question of the dentist’s
experience, ability, and attention to detail, meticulousness and skill. It is seldom possible to assess
the extent such factors influence the results in
treatment studies and clinical evaluations. It is,
however, reasonable to assume that in a clinical
discipline such as endodontics, these factors are
important, because of the technically complicated
nature of many procedures. In endodontic retreatment, the diagnosis and treatment is often complex, and the influence of the operator on the
results cannot be overvalued. So far most clinical
studies have been conducted in academic or
­specialist settings (efficacy), where devices that
T. Kvist
112
s­ubstantially facilitate the technical procedures
are widely spread and will affect the outcome rate
of retreatment procedures. For the future, it is
important that clinical research also is conducted in
general practice where most of teeth with persistent
apical periodontitis are managed (effectiveness).
9.2.2.8 Publication Bias
Dentists and researchers prefer good news. It is
much less appealing to author and publish an article
where the results are disappointing, negative or perhaps much worse than previously published, than to
describe successful treatments. It must be realized
that research projects that attain publication status
are a biassed sample of all researches being conducted. Hence, it is not unreasonable to assume that
our inclination for “good” and positive results leads
to a biassed publication of articles. For example,
imagine a group of clinicians, who have performed
an excellent study from a methodological point of
view about surgical endodontics. But they had a
healing rate of 50% in both the intervention and
control group. With what degree of enthusiasm will
the writing of this article begin? What will the reaction be of journal editors and reviewers, if the article
after all was written and submitted?
9.3
tatements About Prognosis
S
About Apical Periodontitis
in Root-Filled Teeth
Unfortunately, in recent years, careful analyses
of the scientific basis for the methods that we
apply in endodontics as a clinical discipline
within dentistry have demonstrated extensive
shortcomings [11]. The situation is worrying for
diagnostic and treatment procedures as well as
for evaluation of the results of the methods.
It is generally acknowledged that teeth with
inflamed, necrotic and infected pulps can be
treated endodontically to achieve a healthy outcome that can last many years. This bulk of
knowledge has repeatedly been presented in scientific journals reviews and textbooks of endodontics. There are, however, few clinical studies
of high scientific quality [11].
It also well-known that a “successful” outcome is not always the case and that great many
patients present with asymptomatic persistent
signs of apical periodontitis. Statements of the
prognosis of this condition, which is the subject
of this book, suffer from an even greater lack of
evidence than that of primary root canal treatments [7, 11–17]. And this applies both to the
effects of inaction (natural course) and the various forms of treatment (clinical course).
9.3.1
atural History of Apical
N
Periodontitis in Root-Filled
Teeth
The prognosis of a disease without interference
is termed the natural history of disease. Great
many root-filled teeth with apical periodontitis
will not be detected and diagnosed. They remain
unrecognized, because they are asymptomatic,
and even if detected they are not considered for
any intervention. Even, when root-filled teeth
cause mild pain, tenderness or fistulas are considered among the ordinary discomforts of daily
living. Or, the patient may be suffering both
pain and other symptoms for a prolonged period
of time but because of economic limitations, it
has not been able to seek further dental care.
Remarkably little is known about the frequency
of pain and other symptoms as well as general
health hazards from root-filled teeth with apical
periodontitis (see Chap. 4: Consequences).
9.3.2
Clinical Course
The term clinical course has been used to describe
the evolution (prognosis) of disease that has
come under medical or dental care and treated in
a variety of ways that might affect the subsequent
course of events.
9.3.2.1 Retreatment
Chronic periapical asymptomatic lesions as
well as exacerbation or aggravation of persistent apical periodontitis of root-filled teeth
9
Prognosis
may be cured by endodontic non-surgical or
surgical retreatment. There is insufficient scientific support on which to determine whether
surgical and non-­surgical retreatment of rootfilled teeth gives systematically different outcomes, both in the short and long term, with
respect to healing of apical periodontitis or
tooth survival [6, 7, 11].
During the last 20-year period, clinical endodontics has undergone a technological development of rare unprecedented proportions. Rotary
instrumentation alloys have facilitated the painstaking work of removing old root fillings. Super
flexible properties of nickel-titanium instruments
allow root canals to be successfully instrumented
in a predictable way.
An equally significant addition to the endodontic armamentarium is the operating microscope. With its help, previously untreated parts of
the root canal system can be visualized during
both surgical and non-surgical retreatment.
Parallel with the increasing use of the operating
microscope, a wide range of specialized instruments have been developed, primarily in connection with surgical endodontics. In addition, the
introduction of ultrasonic instruments has further
improved treatment options.
Much effort has also been expended on trying
to develop new materials for safer retrograde
sealing of the root canal. Alternatively, technological achievements have significantly changed
the clinical routine of endodontic retreatment
procedures.
In environments of clinical excellence, non-­
surgical as well as surgical retreatment has
shown favourable outcomes on the periapical tissues of “endodontic failures” [17, 18]. It is likely
that more root-filled teeth with apical periodontitis can be successfully treated surgically compared with reports from before microsurgical
techniques were used [17, 19]. Frequency of
periapical healing after retreatment has been
reported to reach approximately 80–90% for
both methods [17, 18]. High-quality clinical
studies of long-­term follow-up of teeth that have
undergone surgical-or nonsurgical retreatment
are so far rare.
113
9.4
Endodontic Retreatment
Need for Research
In the future, there is a need for more high-­quality
research on natural as well as clinical course of
apical periodontitis in root-filled teeth.
Endodontic retreatment methods need to be evaluated whether they are effective in terms of promoting healing of apical periodontitis and
resulting in long-term tooth survival. In this context, it is also important to evaluate the alternatives to retreatment, extraction and replacement
by a tooth-supporting bridge or an implant from
the perspective of quality of life and cost-­
effectiveness [9, 20].
9.5
hort Answers to Clinical
S
Questions
This chapter shows that despite a considerable
documentation gathered through the years about
the management of apical periodontitis in root-­
filled teeth, it is difficult to give evidence-based
answers to many clinical questions. However,
from the bulk of information, it can be concluded
that many individuals will not directly suffer
from the condition but also that the condition
may, in many cases, be cured and possibly save
many of root-filled teeth afflicted by a persistent
apical lesion.
Based on current best empirical and scientific
knowledge, the following general short answers
to “the clinical questions” may be appropriate:
• How does this problem affect my risk of loosening the tooth?
The risk of loosening a root-filled tooth is
higher than for a healthy tooth in general.
To what extent a persistent lesion affects
the risk is not well known.
• Will it affect my general health?
With the current state of knowledge, it is
unlikely that apical periodontitis in root-­
filled teeth would constitute a significant
health risk. But it cannot be entirely ruled
out that the chronic inflammation may
T. Kvist
114
•
•
•
•
r­ epresent a small but contributing negative
factor for poorer health in the long term.
What different options do I have?
If the lesion is asymptomatic and small, some
prefer to do nothing or just to “follow it”
regularly and intervene only if symptoms
occur or if it expands. The other option is to
perform a retreatment. Depending on the
position of the tooth, how it is restored, the
size of lesion, the quality of root filling and
the overall treatment plan, surgical or non-­
surgical retreatment may be appropriate.
How likely is it that retreatment will cure the
tooth?
In cases with persistent disease, surgical or
non-surgical retreatment performed by
skilled specialists using modern armamentarium is able to cure the lesion in about
80–90% of the cases.
Would it be a better idea to take the tooth out?
In most cases no. But if the tooth is afflicted
by periodontal disease or the remaining
tooth substance does not provide conditions for a high-quality restoration, it might
be a better idea.
If so, can it be replaced?
In the majority of cases, a lost tooth can be
replaced by an implant or a fixed
prosthesis.
9.6
Knowledge Gaps
There are few clinical studies of high scientific
quality within the field of endodontics.
Consequently, there are many knowledge gaps
[9]. Further clinical studies with high quality are
necessary to give our patients less vague answers
to the following questions:
• Will root-filled teeth survive long term and
what factors influence the loss of endodontically treated teeth?
• How often will a root-filled tooth with persistent but asymptomatic periapical inflammation result in the occurrence of pain and
swelling?
• Which are the prognostic factors to predict an
exacerbation of asymptomatic periapical
inflammation, particularly in a root-filled tooth?
• How often will retreatment of a root-filled
tooth with apical periodontitis result in overall
better consequences than leaving the condition untreated in the long term?
• What method of retreatment (surgical or non-­
surgical) will have the best results in the long
term?
• How cost-effective are retreatment methods
compared to extraction and replacement?
• Are there any risks to general health when
teeth with a periapical inflammatory process
remain untreated?
Take-Home Lessons
• From the bulk of evidence available
from many years of clinical research
and clinical experience, it stands
clear that root-filled teeth with apical
periodontitis may be successfully
­
retreated in order to give remedy to
symptoms, to establish sound periapical tissues and to promote long-term
survival.
• Few high-quality studies are available to
evidence-based answers to a number of
clinical questions.
• Prognosis for an individual case must
be based not only on the scientific literature but also in rationale and logical thinking based on basic knowledge
of biology and technology and the
conditions that are at hand in every
case.
9
Prognosis
115
Benchmark Papers
• Bergenholtz G, Kvist T. Evidence-based
endodontics. Endod Top. 2014;31:3–18.
This review thoroughly presents the
concept of evidence-based practice and
discusses and how the concept has been
applied to endodontics. The focus is on
treatment procedures in endodontics.
The means used in the process and how
far our knowledge base has reached are
addressed. Aspects are conveyed at the
end on what future research in clinical
endodontics should take into account.
• Swedish Council on Health Technology
Assessment. Methods of diagnosis and
treatment in endodontics—a systematic
review. 2010;Report No 203:1–491. http://
www.sbu.se. A comprehensive review on
the evidence available in Endodontics.
• Del Fabbro M, Corbella S, Sequeira-­
Byron P, Tsesis I, Rosen E, Lolato A,
Taschieri S. Endodontic procedures for
retreatment of periapical lesions.
Cochrane
Database
Syst
Rev.
2016;10:CD005511. An updated complete review on the high-quality studies
(RCT’s) available for different aspects
endodontic retreatment.
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Hodges JS, John MT. Frequency of persistent tooth
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meta-analysis. J Endod. 2010;36:224–30.
Torabinejad M, Corr R, Handysides R, Shabahang
S. Outcomes of nonsurgical retreatment and endodontic surgery: a systematic review. J Endod.
2009;35(7):930.
Petersson A, Axelsson S, Davidson T, Frisk
F, Hakeberg M, Kvist T, Norlund A, Mejàre I,
Portenier I, Sandberg H, Tranaeus S, Bergenholtz
G. Radiological diagnosis of periapical bone tissue
lesions in endodontics: a systematic review. Int Endod
J. 2012;45:783–801.
Tsesis I, Rosen E, Taschieri S, Telishevsky Strauss Y,
Ceresoli V, Del Fabbro M. Outcomes of surgical endodontic treatment performed by a modern technique:
an updated meta-analysis of the literature. J Endod.
2013;39:332–9.
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18. Ng YL, Mann V, Gulabivala K. A prospective study
of the factors affecting outcomes of nonsurgical root
canal treatment: part 1: periapical health. Int Endod
J. 2011;44:583–609.
19. Setzer FC, Shah SB, Kohli MR, Karabucak B, Kim
S. Outcome of endodontic surgery: a meta-analysis of
the literature—part 1: comparison of traditional root-­
end surgery and endodontic microsurgery. J Endod.
2010;36:1757–65.
T. Kvist
20. Torabinejad M, Anderson P, Bader J, Brown LJ,
Chen LH, Goodacre CJ, Kattadiyil MT, Kutsenko
D, Lozada J, Patel R, Petersen F, Puterman I,
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2007;98:285–311.
Alternatives: Extraction and Tooth
Replacement
10
Pernilla Holmberg
It takes a special kind of compass in the field of dental science
and art to understand the present and to navigate the future
of clinical prosthodontics with so many options available!
Abstract
There are different prosthetic treatment options to choose amongst when a
tooth is extracted, and there are numerous factors, both evident and hidden, which will affect the decision-making process and finally result in a
construction best suited for each patient or no construction at all. The dentist must in the decision-making process combine the best available evidence with clinical data, weigh all the factors against each other and in
agreement with the patient choose the best treatment. The restorative dentist of modern age will face an even faster progression of new techniques
and dental materials than before, thus making the prosthetic decision-­
making even more challenging.
10.1
Introduction
extracted tooth or tooth loss per se may have
grave social, professional or psychological conWhen extraction of a root-filled tooth is selected sequences, and for others the loss of a tooth may
due to endodontic treatment failure or inevitable be seen as a natural consequence with no further
because of caries or fracture, the dentist must re-­ implications.
evaluate the existing information about the
The intention of this chapter is to provide the
patient and also gather additional information in reader with a brief outline of available treatment
order to make a treatment decision for the miss- options when a tooth is extracted and leaves a
ing tooth. For some patients the effect of an single-tooth gap and also to present three similar
patient cases who have received three different
tooth replacements. Since there is no possible
way to cover the entire prosthodontic field in
P. Holmberg, DDS
detail in one chapter, the interested reader is
Department of Oral Prosthodontics and National Oral
referred to the extensive and excellent textbooks
Disability Centre, Institute for Postgraduate Dental
on the prosthodontic aspects in detail on replaceEducation, Jönköping, Sweden
e-mail: pernilla.holmberg@liv.se
ment of teeth.
© Springer International Publishing AG 2018
T. Kvist (ed.), Apical Periodontitis in Root-Filled Teeth,
https://doi.org/10.1007/978-3-319-57250-5_10
117
P. Holmberg
118
10.2
Decision-Making
and Evidence-Based
Dentistry
D.V Lindley, Professor in Statistics, stated in
1970: “decision-making is something which concerns all of us, both as the makers of the choice
and as sufferers of consequences”. The process
of clinical decision-making within each clinician
is a complex process, and many minor decisions
both consciously and subconsciously are made
prior to reaching the final decision of which treatment option to choose. Consequently, human
errors can be made during these complex processes, and therefore a good clinician should
reflect on the alternatives, become aware of the
uncertainties, be able to modify his/her judgement on the basis of accumulated evidence, balance the judgement of the risks of various kinds
and finally consider the possible consequences of
each treatment option [1].
Most clinicians have encountered patients
who have basically the same dentitions, yet
slightly different treatment options have been
prescribed. Furthermore, during a professional
life different treatment strategies and philosophies will come and go. Certain will prevail over
others, and to make the context even more complex, observations from medicine and dentistry
suggest that the decisions of healthcare professionals themselves may be highly variable, even
in the case of relatively simple interventions, and
influenced by a number of personal, educational
and economic considerations [2, 3].
Thus, the factors that determine treatment
selection are diverse, and clinical decision-­
making could be consistent and straightforward if there were clear and accepted
guidelines and furthermore if the recommended actions were universally acceptable to
patients and care providers as well as supported by unequivocal evidence [3, 4].
Although there are few real evidence-based
guidelines in fixed and removable prosthodontics, the clinician ought to have an established
practice on which to base his or her treatment
plans as well as to consciously, clearly and
wisely use the latest and best evidence as the
basis for decisions in the treatment of the
i­ndividual patient. In conclusion this implies
integrating personal clinical experience and
skills with the best possible available, external, clinical evidence [5].
10.3
o Arrive at the Correct
T
Prosthodontic Treatment?
“Primum non nocere”! “First do no harm” is still
very much valid and known amongst clinicians
today. It is essential that a clinician is able to
diagnose the problem before deciding on how, or
whether, to treat the patient. Failures of endodontic therapies and resulting in necessary tooth
extractions can make the patients suspicious to
dental treatment. Why did the earlier treatment
result in loss of the tooth? These patients place
greater demands on the skill of the dental team. It
is essential that the clinician is able to diagnose
the problems thoroughly before deciding on how,
or whether, to treat the patient. There is no “correct” way to organize the information-gathering
process, but it is important to have a strategy or a
model in this process and clinical decision-­
making as a way to meet the patient’s expectations and treat the whole patient and not only the
single-tooth loss. The clinician who is not mindful about her or his behavioural basis of care may
well find her/himself providing treatment that
may not have an optimal outcome. The best way
to arrive at a diagnosis is not to collect as much
information as possible but to reject as much as
possible irrelevant information, according to
Webber’s model [6].
The ultimate goal of restorative dentistry is the
preservation of teeth and surrounding oral structures and further to restore appropriate function
and aesthetics. This goal is not always met, and
the proposed prosthesis may not be maintainable
by either the patient or the clinical professionals,
and consequently there will be a likely significant
biological cost. Single-tooth replacement may be
achieved through no replacement at all (NRA), a
removable partial denture (RPD), the use of a
conventional fixed dental prosthesis (FDP), a
resin-bonded fixed dental prosthesis (RBFDP) or
a dental implant-supported single crown (ISSC)
(Fig. 10.1).
10 Alternatives: Extraction and Tooth Replacement
Temporary
Tooth Migration
Patient case
Trauma toothll
Endodontics fails
Extraction
Removable
Prosthesis
Consequences?
No treatment
At all
Permanent ?
Temporary ?
Resin-Bonded
Fixed dental
Prosthesis
Clinical Data
&
Systematic
reviews
Implant supported
single crown
Dental fixed
prosthesis
2-Unit
2-Unit
Survival & (Two-retainer) (single-retainer)
complication
rates ?
Survival &
complication
rates ?
Material
selection ?
PMF
Laboratory
Techniques
Monolithic
CAD /CAM
Decision-making
&
operator’s clinical
experience
Cantilever
EndAbutment
Survival &
complication
Rates ?
All-Ceramic
New Techniques
Scanners
119
Eating
Drinking
Life-style
Smoking
Age
Profession
Medical History
Economy
Social history
Perception
Ability
Motivation
Dental history
Expectiotions
Periapical
Prosthetic
Perio
Remaining teeh
assessment
Caries
Oral hygiene
Radiographic
Panoramic - Assessment
Veneered
Perl
Apical
Oral status
BTW CT
CBCT
Occlusion
Force patiern
Masticatory apparatus
Ridge assessment
Vertical
Aesthetics
Horizontal
Smileline
Soft tissue
contour
Fig. 10.1 A rough outline model for the prosthetic treatment options, single-tooth gap
10.4
Gathering Information
10.4.1 Patient History
10.4.1.1 The Medical History
The patient’s general health must be comprehensively recorded to make sure whether it will
affect the selection of treatment procedures or
not. The dental procedures or the restoration
itself must never be injurious to the health of the
patient. Moreover, the caregiver should make
sure that no member of the dental team or other
patients will be harmed as a consequence of providing dental care to a patient who has an infectious disease.
10.4.1.2 The Social History
It is important to learn about the patient’s lifestyle including eating, drinking and smoking
habits. Lifestyle factors can have a big impact on
both the treatment itself and the outcome and
maintenance of it. In most patients’ lives, the
economy plays a major part which prosthetic
treatment is affordable.
10.4.1.3 The Dental History
By listening to the patient’s own description of
previous experience, it helps the dentist to gain
an impression of the patient’s perceptions of
d­ entistry and of their attitude or motivation for
dental care. It also gives a hint of the patient’s
ability to maintain an acceptable standard of oral
hygiene and the previous dental care given.
10.4.2 The Oral Status
This examination encompasses the charting of
remaining teeth and their status. An evaluation of
the occlusion must be done as well as the health of
the masticatory apparatus. Furthermore, the level
of oral hygiene should be assessed. Individual teeth
may need more specific investigations such as pulp
vitality tests or a thorough assessment of the periodontal status. The clinical collection of information and assessment will be accompanied by a
more or less extensive radiologic examination.
10.4.3 Radiographic Assessments
There are different imaging techniques and each
one has its advantages and disadvantages, which
the clinician must be aware of. The patient must
not be exposed unnecessarily to ionizing radiation and still there is a need to decide on the best
available means to obtain the required and necessary information [7].
P. Holmberg
120
10.4.4 Ridge and Bone Assessment
When selecting between different replacement
options, an evaluation of the ridges is essential.
This may be done by using a gloved finger to
roughly estimate the outline and form. By placing a local anaesthetic and using a sterile probe
with a rubber stopper, the thickness of the mucosa
from the surface to the bone can be measured [8].
Alternatively, this may be achieved using radiographs via a CT scan, but this is more expensive
and not always available for the practising dentist. Bone quality is usually assessed radiographically to determine relative densities.
10.4.5 Space Assessment
Is the available tooth space large enough to incorporate a single tooth? It could very well be that
the available space is too large for one single
tooth or too small. If it is too large, there is an
option to accept the gap as it is or to reduce the
space via orthodontics or by reshaping the neighbouring teeth. If the edentulous space is too
small, there is an option of increasing the space
orthodontically or accepting the gap. Evaluation
of the vertical dimensions is mandatory before
any prosthetic restoration is placed. Lack of vertical space may require an increase in the occlusal vertical dimensions and can be done in many
different ways [9].
10.5
xtraction and Ridge
E
Augmentation
v­ ertical bone loss of 11–22% after 6 months following tooth extraction and that the most rapid
resorption takes place in the first year. The risk of
unfavourable bone loss is particularly high in the
anterior maxilla which is commonly known to
exhibit a thin or even partially absent buccal bone
plate [10–13].
The loss of bone often leaves a condition of
poor quality and quantity of bone which many
times is inadequate for the placement of dental
implants but also changes the gingival contours.
This can also be critical in determining the usefulness of a tooth-borne fixed bridge. If normal
tooth morphology is to be maintained, this will
give wide embrasures at the gingiva and may
result in problems with speech or eating/drinking. The alternative of blocking the embrasures
will lead to a poor aesthetic appearance since the
inciso-gingival connectors will be too long [14,
15] (Figs. 10.2 and 10.3).
Fig. 10.2 Bone deficiencies at site 22 after extraction
resulting in a long inciso-gingival line and poor aesthetic
with a tooth-borne fixed bridge. The gingival outline of
pontic 22 will be situated higher compared to the neighbouring teeth. The aesthetics was solved with pre-­
prosthetic crown lengthening of the front teeth
When a tooth is extracted, it is indisputably followed by a reduction of the alveolar ridge.
Moreover, it is well established that both horizontal and vertical changes of hard- and soft-­
tissue dimensions take place at the edentulous
site. The buccal cortical plate of the alveolar process may be resorbed even prior to tooth extraction as a result of inflammatory tooth disease,
developmental defects and trauma or a combination of these factors. Recent review studies have Fig. 10.3 Staged ridge augmentation at implant site 21
shown horizontal bone loss of 29–63% and compared to simultaneous ridge augmentation at site 11
10 Alternatives: Extraction and Tooth Replacement
Consequently, different measures have been
taken to avoid this bone modelling process such
as immediate implant placement and bone grafting in order to counteract this catabolic process
and preserve the dimensions of the alveolar ridge.
Bone augmentation procedures to rebuild deficient ridge contours are mandatory to enable
optimal dental implant placement and positioning. Sufficient bone volume, favourable three-­
dimensional implant positioning and stable
peri-implant soft-tissue conditions are considered prerequisites to achieve long-term implant
functions and aesthetics [11, 13].
Alveolar ridge rebuilding can be undertaken at
different times during treatment and is generally
categorized as simultaneous or staged. In the
staged approach, the alveolar bone is first reconstructed in an initial surgery. Implant placement is
then carried out 2–6 months later. In contrast, in
the simultaneous approach, implant placement and
alveolar ridge reestablishment are undertaken during the same surgery. The size of the defect affects
the healing time. The simultaneous approach is
obviously the preferred technique by the patient
and clinician alike, since it reduces treatment time
and cost. However, if the residual bone volume
precludes primary implant stability or results in
inadequate prosthodontic implant positioning, the
staged approach is recommended [16, 17].
Thus, the clinician is required to carefully
plan the extraction of a compromised tooth and to
perform the surgical intervention according to a
precise schedule and gentle touch in order to promote favourable hard- and soft-tissue conditions
at the upcoming edentulous site. In addition, it is
possible to reduce healing periods and number of
surgical interventions, especially when implant
treatment is planned [13].
The best way to treat a ridge deficiency is to prevent it from occurring!
10.6
No Replacement at All (NRA)
Sometimes “less is more”! Rarely is NRA chosen
when a single tooth is missing in the aesthetic zone
or in a position which is important to load-­bearing
121
zones. Studies have shown that individuals are
usually more concerned about replacing missing
anterior teeth than posterior teeth, since a great
majority of patients find aesthetics more important
than function. In some cases, the choice of not
replacing a missing tooth could also be due to
socio-economic factors [18]. The clinician must
also be aware of that drifting and tipping of neighbouring teeth to an extraction site are commonly
reported phenomena and make an assessment of
the consequences following tooth extraction. In a
study by Craddock and co-­workers, they found the
teeth mesial to the extraction site had a tendency to
tip distally. The upper teeth showed a higher
degree of tipping and also in subjects with a cuspto-cusp buccal occlusion. Moreover, the tipping of
the tooth distal to the extraction site was more
prevalent in individuals with a reduced overbite
and in the lower arch. The tipping of the distal
tooth could be in some cases extreme [19]. A complete dentition is not always necessary, but the clinician needs to evaluate the risks and consequences
with not replacing a missing tooth and explain and
inform the patient thoroughly.
10.7
emovable Partial Denture
R
(RPD)
A removable partial denture effectively serves
temporarily to stabilize the occlusion and prevent
unwanted drifting of the adjacent and opponent
teeth into the space of the extracted tooth. The
denture is usually made of acrylic or acrylic and
metal. The overall treatment time for this option
is short and the cost can be very low. There is
always a risk of soft-tissue irritation and bone
problems. However, in younger patients, it is a
good therapy waiting for the right age to place a
fixed replacement of the extracted tooth.
Sometimes a removable denture suggested as
temporary substitute turns out to be very well tolerated as a final treatment and preferred option
for replacing a single missing tooth. However,
RPDs are mostly used as a temporary replacement or a compromise because of severe problems with surrounding teeth and perhaps general,
health or economy.
P. Holmberg
122
10.8
ixed Dental Prosthesis
F
(FDP)
It seems apparent that the most ancient dental
prosthetic appliances have been of fixed bridge
work and man has for many centuries tried to
hold artificial or detached natural teeth from one
mouth to another in place by means of wires or
ligatures.
10.8.1 S
urvival and Complication
Rates
Fixed dental prosthesis for teeth have taken a
variety of designs throughout the history. The
initial placement of a fixed dental prosthesis
is rarely the end of treatment and many times
the patient enters the “cycle of rerestoration”
leading to expansion of prostheses carrying
increased biological and technical risks and
consequently higher costs of dental care. Socioeconomic factors and better oral hygiene regimens with patients included in regular recall
programmes have led to an increased number of
teeth and to a shift from fully to more partially
edentulous patients over the past decades. This
has resulted in a trend towards higher frequencies of fixed dental prostheses. Fixed dental
prosthesis (FDP) are associated with the sacrifice of sound tooth tissue and inherent risks of
pulp injury [20–23]. One study conducted
amongst 66 practising dentists showed that
70% of treatment recommendations resulted in
an increased number of restored surfaces [22].
A considerable disadvantage with bridgework
replacing a single tooth is that the neighbouring
healthy teeth have to be involved, affected and
damaged. Owing to the variety of techniques
employed and materials used, failing reconstructions may be attributed to several causes. Some
studies attribute over 50% of failures to the dentists and materials used. Moreover, biological
and technical complications have been reported
in a variety of studies including secondary caries,
loss of retention and marginal defects [22].
Failure of a FDP is not particularly alarming per se, but the biologic consequences that
many times will ensue may be the cause of
great concern. Caries is the most reported
cause of prosthesis failure and results in loss
of dental hard structures, structural compromises and loss of abutment teeth, while loss of
retention of the FDP was the most common
technical complication [21]. Goodacre and
Spolnik [24] reported that 3–23% of the abutment teeth used requires endodontic treatment
after placement of a FDP. Abutment fractures
and endodontic failures present additional
complications to FDP since abutment teeth
that have been further weakened must support
larger prostheses [24]. In a meta-­analysis conducted by Scurria et al. [25], prosthesis survival dropped to 69% at 15 years, as in
accordance of another study where Lindquist
and Karlsson [26] indicated a survival rate of
fixed partial prosthesis that drops significantly
after approximately 10 years and after 20 years
the survival rate was 65%.
10.8.2 Material Selection
The evolution in material science has led to the
introduction of new framework materials, and
the tradition with using metal-based reconstructions for fixed dental reconstructions is
partially changing in favour for all-ceramic
materials, e.g. monolithic materials rather than
a framework with a veneer. In a recent systematic review (Pjetursson et al. [20]) comparing
survival rates of all types of all-ceramic FDPs
with conventional metal-ceramic FDPs, the
incidence of framework fractures was significantly higher for reinforced glass-ceramic FDP
as well as infiltrated glass-ceramic FDPs. The
incidence for ceramic fracture and loss of
retention was significantly higher for densely
sintered zirconia FDPs compared to metalceramic constructions. In conclusion, the survival rate for all-ceramic FDPs was lower than
for metal-ceramic FDPS [20].
10 Alternatives: Extraction and Tooth Replacement
10.8.3 C
antilever Fixed Dental
Prostheses
Pjetursson et al. [27] conducted a review on cantilever fixed partial prosthesis where the cumulative failure rate was 18.2% after a 10-year
follow-up time, as compared with the results for
conventional end-abutment-supported fixed partial prosthesis which showed a 10.9% failure
rate. Of the abutment teeth considered vital at
the time of cementation, 32.6% lost their pulp
vitality over a period of 10 years, and this was
the most common biological complication [27].
In an earlier study by Karlsson [28], two-thirds
of the failed cantilever fixed partial prosthesis
had a terminal root-canal-treated abutment indicating that cantilever fixed partial prosthesis was
more prone to failure, if based on a nonvital terminal abutment. Randow and Glantz [29] conducted a study on root-canal-treated teeth and
found that the pain threshold was almost twice as
high on these nonvital teeth as compared to vital
teeth. Comparing one-cantilever pontic with
fixed partial prosthesis with multiple extensions,
there was no significant difference [27]. Another
common biological complication was caries at
the abutment teeth, and in several studies an
association between loss of retention and secondary caries was noted. This might be debatable which of the two conditions occurred first
and led to the other. The most frequent technical
complication was loss of retention. In conclusion, it seems that there is a higher risk for biological and technical complications for the
cantilever FPP compared to the conventional
end-abutment-supported fixed partial prosthesis
after 10 years and the estimated survival rate is
81.8% after a 10-year observation period [27].
10.9
esin-Bonded Fixed Dental
R
Prosthesis (RBFDP)
The resin-bonded fixed dental prosthesis provides a method for replacing missing teeth or
splinting periodontally weakened teeth in the
123
anterior regions of the mouth. This method has
both short-term and long-term benefits in that
prosthesis can be placed with minimal or no
tooth preparation [30]. In the early 1970s,
Rochette developed and introduced a more
complex procedure compared to the previous
bonded acrylic denture tooth. The bridge framework was laboratory-­manufactured and perforated with tapering holes in order to lock the
framework in place, covering the lingual surfaces and with a more aesthetic pontic [30].
Livaditis and co-­workers from Maryland in the
USA extended it further to include the posterior
region and also developed the etched alloy
technique to overcome the shortcomings with
the Rochette technique.
10.9.1 S
urvival and Complication
Rates
The survival rates vary widely between studies,
but debonding is the most frequent occurring
technical complication. When there are no reliable mechanical and chemical bonds between
metal/resin and dental/resin surfaces, the retention lock will degrade faster over time being [30,
31]. Pjetursson et al. [32] has shown a cumulative
rate of 19.2% during a 5-year observation time.
The debonding was most frequent in the metal-­
ceramic RBFDPs with a perforated framework,
and the posterior bridges showed a higher rate as
well with debonding compared to the anterior.
Since the development of the first RBBs in the
1970s, there have been significant changes in the
design, the materials used and the tooth preparation to improve the longevity of the prosthesis.
10.9.2 Material Selection
The first all-ceramic RBFDPs were introduced in
the early 1990s as to benefit from the advantages
with a predictable adhesive cementation procedure and debonding was seldom a complication,
but they showed a high risk for fracture due to
124
their brittleness. In order to improve their stability, the design was changed from two-retainer to
single-retainer cantilever RBFDP, and consequently the survival rates were improved. In a
retrospective study of all-ceramic single-retainer
cantilever resin-bonded fixed dental prostheses
by Sailer et al. [33], there were no problems with
debonding and no catastrophic failures, thus
100% survival after a 6-year follow-up.
10.10 Implant-Supported Single
Crown (ISSC)
The use of an implant-supported single crown
preserves the adjacent teeth and the surrounding
oral tissues. Consequently, there is no risk of
loss of vitality of abutment teeth or further
weakening of an already weak abutment tooth
due to tooth substance loss. Today, many
patients also oppose and reject treatments which
involve tooth preparations; thus, the osseointegration method has opened up possibilities for
implant-supported single crowns for replacing a
missing tooth [34–36]. In the early days of
implants, the primary goal was osseointegration, but now it is taken for granted and even for
the implant to remain in function for years.
Today the focus has shifted towards the aesthetics and how to augment and contour the alveolar
ridge.
10.10.1 S
urvival and Complication
Rates
The replacement of missing teeth, especially in
the anterior zone, has always been a challenge for
the dentist, and a major challenge for the restorative dentist is to provide the patient with an
implant-supported crown which is in harmony
with the neighbouring teeth and soft tissue in
order to restore function and aesthetics. It is of
great importance to place the implants in a
P. Holmberg
p­ osition to optimize the emergence profiles of the
restoration to achieve this, called currently “the
restorative-driven surgical concept” [37].
Earlier research concerning the use of dental
implants (DI) in partial edentulism and single-­
tooth replacement reported survival rates of
93.6–97.5%, respectively, during a 5-year follow-­up, and the prosthetic complications were
relatively low with the most common complication being abutment or screw loosening [35, 38,
39]. In concordance, a newer systematic review
by Jung et al. [40] showed survival rates mounting to 97.2% at 5 years and 89.4% after 10 years.
Biological, technical and aesthetic complications
were frequent with the highest cumulative complication rate with soft-tissue complications
encompassing peri-implantitis, fistulas, gingivitis
or other signs of inflammation. Technical complications such as abutment and screw loosening
also showed a high rate, mostly due to one older
study who reported on first generation of SCs on
Brånemark implants. And if excluded from the
study, the cumulative incidence of screw loosening decreased. Fractures of components, such as
implants, abutments and occlusal screw were rare
complications.
10.11 W
hich Prosthetic Treatment
for the Single-Tooth Gap?
Comparing Fixed Dental
Prostheses (FDPs)
and Implant-Supported
Single Crowns (ISSCs)
The question confronting each clinician is when
to apply which prosthetic treatment option and
to use these therapeutic approaches to their maximum benefit for the patient [34]. Today, a
greater demand is placed on the diagnostic and
treatment planning by the clinician, as a consequence of the introduction of newer surgical and
restorative techniques as well as newer restorative materials that has significantly expanded
10 Alternatives: Extraction and Tooth Replacement
125
the available treatment options. In an ideal pros- psychological profile of each patient. The
thetic world, the treatment decisions should be patients’ preferences as well as their willingness
based on well-­performed reviews of the avail- to pay for different alternatives will finally result
able evidence and, if possible, on formal quanti- in the “best option” in each for the particular contative evidence synthesis and meta-analysis [41]. text and clinical situation.
Since there is no clear-cut percentage of survival
rates between the two options, the decision-making process is partially based on operator’s clini- 10.12 Replacing a Single Missing
cal experience, skill and inclinations and patient
Tooth—Analysis
preferences [42].
and Treatment Planning
In the daily clinical practice, patient and clinician satisfaction is not only influenced by sur- These three patients have in common that they
vival rates. Survival is usually defined as the all have experienced dental trauma in relatively
implants or prostheses remaining in situ with or young age where the upper right central incisor
without modification during the observation have undergone root canal treatment but later
time, but not necessarily free of complications the tooth has been extracted. They have
[43]. Both implant-supported crowns and tooth-­ received different prosthetic treatments even
supported fixed dental prostheses exhibit a vari- though the same tooth is missing. The examety of complications. One meta-analysis of 5- and ples are given to show the reader how different
10-year survival rates of FDPs and ISSCs, per- factors in the information gathering affect the
formed by Pjetursson et al. [41], showed an esti- treatment option selected.
mated 5-year survival rate of conventional
tooth-supported fixed dental prostheses of 93.8%,
cantilevered FDPs of 91.4% and implant-­ 10.12.1 Case 1
supported single crowns of 94.5%, respectively.
After 10 years of function, the estimated survival A 19-year-old man was referred for replacedecreased to 89.2% for conventional FDPs, ment of a missing maxillary central incisor due
80.3% for cantilever FDPs and 89.4% for to trauma and later on failed endodontics. The
upper right lateral and central incisors were
implant-supported SCs.
Failures of conventional FDPs were most fre- intruded at the trauma occasion when the
quently attributed to biological factors like caries patient was 11 years old. The teeth were reposiand loss of pulp vitality as compared to more tioned, fixated and underwent root canal thertechnical complications for the ISSCs such as apy. Two years later the central incisor showed
ceramic fractures or chipping, abutment or screw ankylosis, and therefore a decision was made to
decoronate the tooth in order to preserve the
loosening and loss of retention [41].
In summary, the clinician cannot solely use alveolar ridge while the patient was growing
the published estimated survival and complica- and was replaced with a temporary removable
tion rates on group level to make clinical decision denture [44]. Orthodontic treatment was perfor the individual patient, since there is no scien- formed due to inadequate space for the upper
tific evidence for the superiority of any of the canines and a prenormal growth development.
options. The wise clinician and dental team make The treatment with a single-tooth implant was
their decision-making on the best available evi- postponed until the patient turned 20 so most of
dence together with a professional and meticu- the developmental growth would have taken
lous evaluation of the unique medical, oral and place (Figs. 10.4–10.7).
126
P. Holmberg
Fig. 10.4 The tooth gap shows a thick gingiva biotype
[45], square teeth and a low lipline (which is not shown at
these photos). Triangular teeth are supposed to pose a
greater risk for failed aesthetics, and this risk is most
likely associated with the emergence profile and tissue
support [46]. Minor vertical tissue deficiency. Surgery
was performed according to a two-stage protocol, and the
patient underwent a rigorous oral hygiene schedule
Fig. 10.5 Three months after the implant was placed, a
temporary crown with a moderate emergence profile was
fabricated by the dental technician using a titanium post
for temporary restorations in order to condition the
mucosa and attain soft-tissue stability
Figs. 10.6 and 10.7 A screw-retained all-ceramic
crown. The implant shoulder was located a bit too far
palatally due to the loss of the horizontal bone which
resulted in a restoration with a ridge—lap design.
Satisfactory aesthetics
10 Alternatives: Extraction and Tooth Replacement
127
10.12.2 Case 2
A 14-year-old girl was referred for an interim restoration replacing the upper right central incisor
due to an old trauma and failed endodontics and in
waiting for an implant replacement. The patient
couldn’t accept the aesthetics of the resin-­bonded
fixed restoration metal/ceramics and which also
had debonded several times. The patient was very
anxious in the dental treatment situation so all
dental treatment was performed under sedation
with nitrous oxide. A single-tooth replacement
with an implant is planned but the patient is too
young for such a treatment (Figs. 10.8–10.10).
Fig. 10.8 Note the greyish discoloration and the disharmony with the adjacent teeth. Deficient horizontal
width of the hard tissue at the site. Medium gingiva biotype. This patient will probably need horizontal bone
augmentation prior to implant installment and/or softtissue grafting
Figs. 10.9 and 10.10 A new resin-bonded bridge in
lithium disilicate glass-ceramic for the press technique
was performed and cemented according to the instructions
of the manufacturer. Only one tooth supports the resin-­
bonded bridge. Better aesthetics and harmony in the outline were achieved, and the young patient was satisfied.
Efforts have been made to interlock the upper right lateral
incisor with the pontic, in order to prevent it from migration with continued growth. Regular and continued check-­
ups whether orthodontic site preparation will be needed in
the future for a single-tooth implant
128
P. Holmberg
10.12.3 Case 3
A 26-year-old man was admitted for improving
the aesthetics in the frontal upper jaw. The
patient’s new girlfriend had persuaded the patient
to seek dental treatment. The upper right central
incisor was lost due to failed endodontics following a trauma. The tooth was extracted and replaced
with a resin-bonded bridge in metal-­ceramic. He
did not wish for a prolonged and extensive dental
treatment since he suffered from dental anxiety.
He declined treatment with extraction of two premolars and orthodontic site preparation for a single-tooth implant (Figs. 10.11–10.15).
Figs. 10.11 and 10.12 Not enough restorative space for
a dental implant at site 11. Grey discolouration of the left
maxillary central incisor. Triangular tooth shape with thin
gingival biotype at least where the snuff induced lesions
can be seen but also elsewhere. This patient is at greater
risk for soft-tissue recession. The interocclusal space for
any restoration is advantageous. Medium lip line. Midline
shift probably due to tooth migration
Figs. 10.13–10.15 An all-ceramic tooth-supported
fixed dental prostheses and an all-ceramic veneer were
planned for and executed to optimize the aesthetic.
Prior to treatment decision, a wax set-up was made.
Care was taken not to place the margins of the crown
subgingivally due to the already present soft-tissue
recessions. Better harmony was achieved with the midline shift and tooth shape. In this particular case, the
biologic price consisted of the loss of tooth substances
when being prepared for a fixed dental prosthesis.
10 Alternatives: Extraction and Tooth Replacement
10.13 Outlook Prosthetic
Treatments in 2017
Today, the field of dental science and art have
changed dramatically, and the restorative dentist has a greater number of options available
for tooth preparation techniques, impression
taking and restorative materials than in the past.
It has not only changed the way dentists run
their practice but also the dental laboratory
world. Mechanical engineering, laser milling
techniques and lately 3D printing and design
have emerged and are evolving in an increasing
pace. The introduction of intraoral scanners in
2003 made it possible to switch from the analogue to the digital world, and today there is a
wide use of CAD/CAM in the dental laboratory
environment and dental offices. The intraoral
scanners in 2017 can be used for almost any
indication for a ­
tooth-­
supported construction
compared to the implant-­supported constructions since they do not have a periodontal ligament and show less flexibility than a natural
tooth. If a construction does not show a 100%
fit, the tooth can be displaced by force but not
the implant. All new techniques and materials
have a learning curve for both the dental team
and the dental technician, and thus all dental
situations cannot be scanned which consequently will lead back to more conventional
methods. Combining scanning technology and
CAD/CAM procedures makes it possible to
reduce clinical and dental laboratory working
time significantly [47].
Milling and printing of implant-supported
and tooth-borne fixed prostheses are considered to be the “golden” standard today, and the
traditional waxing up and casting in gold or
129
precious alloys has given way for these newer
techniques. Alloys having a high proportion of
precious metals in the fabrication of porcelain-metal fused constructions have been
slowly replaced/substituted by cobalt-chromium. Increasing aesthetic demands from
patients as well as clinician have made it possible for new full-ceramic materials and systems to emerge. A paramount change of
concept was the introduction the PROCERA
system in 1993 since the white alumina copings could be produced in the dental laboratory using CAD/CAM. Further development
came with zirconia CAD/CAM copings which
were introduced in the late 1990s. This material was stronger and in a sense “self-healing”
when small cracks occurred and therefore
more suitable for load-­bearing reconstructions
such as posterior FDPs. It is now possible to
stain zirconia in tooth-shade colours and use it
as a monolithic restoration to avoid veneering
material prone to chip off effects. The coloured
zirconia is milled out of the same material as
the core material. Polished zirconia is the least
abrasive dental material available [47, 48].
The field of implant therapy has evolved at
least as quickly as that of restorative dentistry in
general. The use of wider varieties of implant
diameters, lengths and morphologies and implant
surface technology has changed many of the
basic tenants of implantology. The time necessary to attain osseointegration has been significantly shortened, and the initial strength of the
osseointegrative bond is dramatically increased.
Finally, the understanding of implant capabilities
in various sites and load applications continues to
evolve and has given us better tools to maximize
treatment outcomes for our patients.
P. Holmberg
130
Take-Home Message
• Few real evidence-based guidelines exist
in fixed and removable prosthodontics.
• The best way to treat a ridge deficiency
is to prevent it from occurring!
• The clinician is required to carefully
plan the tooth extraction in order to optimize the hard- and soft-tissue conditions at the edentulous site.
• Failures of conventional FDP are most
frequently attributed to biological factors like caries and loss of pulp vitality.
• Cantilever FDP present higher clinical
risk compared to conventional FDP.
• Adequate retention and long-life expectancy for RBFP depend on framework
material chosen, how many retainers
incorporated and precise intra-enamel-­
placed preparations that add mechanical
retention.
• Scientific evidence suggests that treatment with implant-supported SCs in a
tooth gap can be considered as a safe
and predictable option.
at least 5 years. Clin Oral Implants Res.
2004;15:654–66.
• Pjetursson BE, Tan K, Lang NP, Brägger
U, Egger M, Zwahlen M. A systematic
review of the survival and complication
rates of fixed partial dentures (FDPS) after
an observation period of least 5 years. IV
Cantilever or extension FDPs. Clin Oral
Implants Res. 2004;15:667–67.
• Pjetursson BE, Brägger U, Lang NP,
Zwahlen M. Comparison of survival and
complication rates of tooth-supported
(FDPs) and implant-supported FDPs and
single crowns (SCs). Clin Oral Implants
Res. 2007;18(Suppl 3):97–113.
• Pjetursson BE, Sailer I, Makarov NA,
Zwahlen M, Thoma DS. All-ceramic or
metal-ceramic tooth-supported fixed
dental prostheses (FDPs)? A systematic
review of the survival and complication
rates. Part II: Multiple-unit FDPs. Dent
Mater. 2015;31:624–39.
References
Benchmark Papers
The following references are in particular
important since they are all systematic
reviews or meta-analysis of the available
evidence and contribute to the treatment
decision-making phase:
• Jung RE, Zembic A, Pjetursson BE,
Zwahlen M, Thoma DS. Systematic review
of the survival rate and the incidence of
biological, technical, and aesthetic complications of single crowns on implants
reported in longitudinal studies with a
mean follow-up of 5 years. Clin Oral
Implants Res. 2012;23(Suppl 6):2–21.
• Ken T, Pjetursson BE, Lang NP, Chan
ES. A systematic review of the survival
and complication rates of fixed partial
dentures after an observation period of
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10 Alternatives: Extraction and Tooth Replacement
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11. Tan WL, Wong TL, Wong MC, Lang NP. A systematic review of post-extractional alveolar hard and soft
tissue dimensional changes in humans. Clin Oral
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12. Hof M, Pommer B, Strbac GD, Sütö D, Watzek
G, Zechner W. Esthetic evaluation of single-tooth
implants in the anterior maxilla following autologous bone augmentation. Clin Oral Implants Res.
2013;24(Suppl A100):88–93.
13. Kuchler U, von Arx T. Horizontal ridge augmentation
in conjunction with or prior to implant placement in
the anterior maxilla: a systematic review. Int J Oral
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14. Kubilius M, Kubilius R, Glwiznys A. The preservation of alveolar bone ridge during tooth extraction.
Stomatologija. 2012;14:3–11.
15. McCord JF, Grant AA, Youngson CC, Watson RM,
Davis DM. Fixed prosthodontic options. In: Parkinson
M, comissioning editor. Missing teeth: a guide to
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using autogenous block grafts and the guided bone
regeneration technique with collagen membranes:
a clinical study with 42 patients. Clin Oral Implants
Res. 2006;17:359–66.
17. Buser D, Bornstein MM, Weber HP, Grutter L,
Schmid B, Belser UC. Early implant placement with
simultaneous guided bone regeneration following
­
single-­tooth extraction in the esthetic zone: a crosssectional, retrospective study in 45 subjects with a 2–4year follow-up. J Periodontol. 2008;79(9):1773–81.
18. Elias AC, Sheiham A. The relationship between satisfaction with mouth and number and position of teeth.
J Oral Rehabil. 1998;25:649–61.
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A. Occlusal changes following posterior tooth loss
in adults. Part 2. Clinical parameters associated with
movement of teeth adjacent to the site of posterior
tooth loss. J Prosthodont. 2007;16:495–501.
20. Pjetursson BE, Sailer I, Makarov NA, Zwahlen M,
Thoma DS. All-ceramic or metal-ceramic tooth-­
supported fixed dental prostheses (FDPs)? A systematic review of the survival and complication rates. Part
II: Multiple-unit FDPs. Den Mater. 2015;31(6):624–39.
21. Avivi-Arber L, Zarb GA. Clinical effectiveness of
implant supported single-tooth replacement. The Toronto
study. Int J Oral Maxillofac Implants. 1996;11:311–21.
22. Brantley CF, Bader JD, Sugars DA, Nesbit SP. Does
the cycle of re-restoration lead to larger restorations?
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131
23. Ken T, Pjetursson BE, Lang NP, Chan ESY. A systematic review of the survival and complication rates of
fixed partial dentures after an observation period of at
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24. Goodacre CJ, Spolnik KJ. The prosthodontic management of endodontically treated teeth: a literature
review. Part I. Success and failure data, treatment concepts. J Prosthodont. 1994;3:243–50.
25. Scurria MS, Bader JD, Shugars DA. Meta-analysis
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26. Lindquist K, Karlsson S. Success rate and failure for
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27. Pjetursson BE, Tan K, Lang NP, Brägger U, Egger
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(FDPS) after an observation period of least 5 years.
IV Cantilever or extension FDPs. Clin Oral Implants
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28. Karlsson S. Failures and length of service in fixed
prosthodontics after long-term function. A longitudinal clinical study. Swed Dent J. 1989;13:185–92.
29. Randow K, Glantz PO. On cantilever loading of vital
and non-vital teeth. An experimental clinical study.
Acta Odontol Scand. 1986;44:271–7.
30. Simonsen R, Thomson V, Barrach G. Historical development of the etched fixed partial denture. In: Simonsen
R, editor. Etched cast restorations: clinical and laboratory techniques. Chicago, IL: Quintessence Publishing
Co; 1983. p. 15–32.
31. Livaditis GJ, Thomson VP. Etched casting: an
improved retentive mechanism for resin-bonded
retainers. J Prosth Dent. 1982;47:52–8.
32. Pjetursson BE, Tan WC, Tan K, Brägger U, Zwahlen
M, Lang NP. A systematic review of the survival and
complication rates of resin-bonded bridges after an
observation time of at least 5 years. Clin Oral Implants
Res. 2008;19:131–41.
33. Sailer I, Bonani T, Brodbeck U, Hämmerle
C. Retrospective clinical study of single-retainer
cantilever anterior and posterior glass-ceramic resin-­
bonded fixed dental prostheses at a mean follow-up of
6 years. Int J Prosthodont. 2013;26(5):443–50. https://
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34. Fugazotti PA. Evidence-based decision making:
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35. Andersson B, Ödman P, Lindvall A-M, Lithner
B. Single tooth restorations supported by osseointegrated implants: results and experiences from a prospective study after 2–3 years. Int J Oral Maxillofac
Implants. 1995;10:702–11.
36. Albrektsson T, Zarb G, Worthington P, Eriksson
AR. The long-term efficacy of currently used dental
implants: a review and proposed criteria of success.
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38. Lindh T, Gunne J, Tillberg A, Molin M. A meta-­
analysis of implants in partial edentulism. Clin Oral
Implants Res. 1998;9:80–90.
39. Priest G. Single-tooth implants and their role in preserving remaining teeth: a 10-year survival study. Int
J Oral Maxillofac Implants. 1999;14:181–8.
40. Jung RE, Zembic A, Pjetursson BE, Zwahlen M,
Thoma DS. Systematic review of the survival rate and
the incidence of biological, technical, and aesthetic
complications of single crowns on implants reported in
longitudinal studies with a mean follow-­up of 5 years.
Clin Oral Implants Res. 2012;23(Suppl 6):2–21.
41. Pjetursson BE, Brägger U, Lang NP, Zwahlen
M. Comparison of survival and complication rates of
tooth-supported (FDPs) and implant-supported FDPs
and single crowns (SCs). Clin Oral Implants Res.
2007;18(Suppl 3):97–113.
42. Bouchard P, Renouard F, Bourgeois D, Fromentin O,
Jeanneret MH, Beresniak A. Cost-effectiveness modeling of dental implant vs. bridge. Clin Oral Implants
Res. 2009;20:583–7.
43. Pjetursson BE, Asgeirsson AG, Zwahlen M, Sailer
I. Improvements in implant dentistry over the last
44.
45.
46.
47.
48.
decade: comparison of survival and complication rates
in older and newer publication. Int J Oral Maxillofac
Implants. 2014;29(Suppl):308–24.
Cohenca N, Stabholz A. Decoronation—a conservative method to treat ankylosed teeth for preservation of alveolar ridge prior to permanent prosthetic
­reconstruction: a literature review and case presentation. Dent Traumatol. 2007;23:87–94.
Kois JC, Kan JY. Predictable peri-implant gingival
aesthetics: surgical and prosthodontic rationales.
Pract Proced Aesthet Dent. 2001;13(9):691–698;quiz
700, 721–2.
Takei HH. The interdental space. Dent Clin North
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Derksen W, Wismeijer D, Hanssen S, Tahmaseb
A. Dental technician of the future. Forum Implantol.
2015;11(1):12–20.
Ioannidis A, Reichart D, Fehmer V, Sailer
I. Benefits and current limitations of monolithic
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Implantol. 2015;11(1):22–7.
Index
A
Antimicrobial resistance, 28
Apical fenestration, 44
Apical granuloma, 27
Apical lesions, 100
Apical periodontitis
clinical questions, 113–114
endodontic epidemiology, 8
cross-sectional studies, 8–9
longitudinal studies, 9–12
methodology selection, 12
frequency and prevalence of, 14
history, 112
incidence of, 15, 16
on intraoral radiographs, 50
nonendodontic lesions misdiagnosed as, 49
population surveys vs. clinical studies, 8
prevalence of, 36
prognosis, 112–113
radiographic examination, 12–13
risk indicators
individual-specific, 15
tooth-specific, 14–15
Asymptomatic lesions, 34, 35
Asymptomatic tooth
lesion, 51
widened periapical contour, 51
Atypical odontalgia, 45
B
Biofilm. See also Root canal biofilms
bacteria in, 23
extra-radicular, 25, 26
formation, 22, 24, 26
growth and maturation of, 25
infections, 3
in root-filled teeth, 26
matrix, 25
© Springer International Publishing AG 2018
T. Kvist (ed.), Apical Periodontitis in Root-Filled Teeth,
https://doi.org/10.1007/978-3-319-57250-5
Bleeding control, 84
Bone augmentation, 121
Buccal cortical plate, 120
Buccal entrance, 80
C
Cardiovascular disease (CVD), 35
CBCT. See Cone beam computed tomography (CBCT)
Cell death, 28
Chronic apical lesions, 26
Chronic apical periodontitis, 35
Chronic inflammatory lesion, 27
Chronic periapical asymptomatic lesions, 112
Clinical decision making, descriptive projects, 55
endodontic retreatment
benefits, 58–59
decision making, 57–58
praxis concept, 58
personal values, 58
Clinical decision making, prescriptive projects, 59
autonomy and information, 61–62
monitors and blunters, 62–63
ethics, 60
evidence-based decision making, 61
expected utility theory, 61
informed consent, 63–64
authorized, 65
information about risks, 64
information about treatment, 64
information on costs, 64
Strindberg system, 60–61
Clinical research, apical periodontitis
biasses, 109
confounding, 110
measurement, 110
sampling, 109–110
selection, 110
case reports, 105
133
Index
134
Clinical research, apical periodontitis (cont.)
case-control studies, 105
clinically relevant outcomes, 111
database-based studies, 105
efficacy and effectiveness, 111–112
loss to follow-up, 111
methods, 104–105
PICO concept, 108
prospective cohort studies, 105
publication bias, 112
randomized controlled trials, 105–108
statistical analysis, 110–111
statistical and clinical significance, 111
systemic reviews and meta-analysed, 108
Colonizers, 23–25
Cone beam computed tomography
(CBCT), 3, 12, 44, 48, 90, 91
advantages, 47
disadvantages, 47
in endodontics, 48
Consequences
for dentists
diagnosis, 36–37
liability, 37–38
specialists need, 38
training and armamentarium, 38
for third party, 39
Consequences for patients
biological
flare-ups of asymptomatic lesions, 34
local spread of disease, 34
loss of tooth, 34
persistent pain, 34
systemic effects, 35
economic aspects, 36
psychological consequences, 35
Contemporary endodontics, 1
Coronary heart disease (CHD), 35
D
Decision making. See also Clinical decision making
and evidence-based dentistry, 118
evidence-based, 61
philosophical justification, 65–66
Dental care
high-quality, 2
medical and, variation in, 57
Dental implants (DI), 3, 124
Dentistry
decision making and evidence-based, 118
goal of restorative, 118
Dentists, 51, 62–64, 68, 117, 119
consequences for, 36–38
role, 39
Diagnostic methods, apical periodontitis
arguments for benefit of doubt strategy, 49–50
clinical differential diagnosis
apical fenestration, 44
nonodontogenic pain, 45
pulpitis, 45
vertical root fracture, 44–45
diagnostic determination, situations
and guidelines, 50–51
diagnostic strategy, 49
exceptions from benefit from the doubt strategy, 50
options, 55–56
radiographic diagnosis, uncertainties in, 45–49
radiographic evaluation
reliability, 46–47
validity, 47–48
radiographic examination, 45–49
Disease, defined, 3–4
Dormant cell, 27
E
Endodontic microorganisms
resistance of, 28
tolerance of, 28–30
Endodontic retreatment decision making, 56, 57
Endodontics, 2, 21
CBCT in, 48
contemporary, 1
infections, persistent, 21
modern, 2
Endosolv™, 94
Enterococcus faecalis, 24, 29
Expected utility theory (EUT), 61
Extraction
and ridge augmentation, 120
of root-filled tooth, 117
Extra-radicular colonization, 25–26
F
Fixed dental prosthesis (FDP), 122, 124, 125
cantilever, 123
material selection, 122
survival and complication rates, 122
G
Granulomas, 27
Granulomatous tissues,
Mycobacterium tuberculosis in, 27
Guttasolv™, 94
H
Health-care procedure, variation in, 57
High-quality dental care, 2
Host-microbe interactions, 26–27
I
Implant-supported single crown (ISSC), 124
Intraoral radiographs, apical periodontitis on, 50
ISSC. See Implant-supported single crown (ISSC)
Index
J
Juxtaradicular radiolucency, 82
L
Lesion
asymptomatic, 34, 35
chronic apical, 26
chronic inflammatory, 27
chronic periapical asymptomatic, 112
nonendodontic, 49
periapical, 76
M
Microbial biofilm communities, 22
Microbial resistance vs. tolerance, 27
Microbiota, 22
Mineral trioxide aggregate (MTA), 85
Modern endodontics, 2
Mycobacterium tuberculosis, 27
N
Naturalist theory, 4
Neuralgia, trigeminal, 45
Neuropathic pain, 45
No Replacement at All (NRA), 121
Nonendodontic lesions, misdiagnosed as apical
periodontitis, 49
Nonodontogenic pain, 45
Non-surgical retreatment, apical periodontitis
access preparation, 93
chemical disinfection
chlorhexidine and iodine-potassium iodide, 98
EDTA, 98
irrigation, 97–99
sodium hypochlorite, 98
coronal restoration assessment, 91–92
crowns, cores and posts removal, 92
follow-up, 99–101
gutta-percha and sealer removal, 93–94
instrument fractures, 95–97
instrumentation of apical part, 94–95
inter-appointment dressings, calcium hydroxide, 99
ledges, 95
magnification and illumination, 91
overinstrumentation, 97
perforations, 97
plastic carriers removal, 94
root filling material removal, 93
root filling procedure, 99
rubber dam and aseptic working field, 93
solvents removal, 94
X-ray examination, 90–91
Normativist theory, 4
NRA. See No Replacement at All (NRA)
O
Oral status, patient, 119
Orthopantomogram, 79
135
P
PAI. See Periapical index (PAI)
Patient
dental history, 119
medical history, 119
social history, 119
Periapical expressions, radiological and histological, 13
Periapical index (PAI), 13, 46
Periapical lesions, 76
Periapical radiolucency, 82
Persistent endodontic infections, 21
Phantom tooth pain. See Atypical odontalgia
Phenotypic tolerance, 28
PICO concept, 108, 109
PICO model, 108
PMNs, 27
Prosthetic treatment, 2017, 129
Prosthodontic treatment, 118–119
single-tooth gap, 124
Pulpitis, 45
Q
Quorum sensing, 25
R
Radiographic assessments, 119
Randomized controlled trials (RCTs), 105
design, 106
PICO concept for, 109
RBFDP. See Resin-bonded fixed dental prosthesis
(RBFDP)
RCTs. See Randomized controlled trials (RCTs)
Receiver Operating Characteristic (ROC) curve, 47
Referred pain, from temporomandibular disorder, 45
Removable partial denture (RPD), 121
Resin-bonded fixed dental prosthesis (RBFDP), 123
material selection, 123–124
survival and complication rates, 123
Resistance vs. tolerance, 27–29
Resuscitation-promoting factors (Rpf), 27
Ridge and bone assessment, 120
Ridge augmentation, 120
extraction and, 120–121
Risk indicators, for apical periodontitis
individual-specific, 15
tooth-specific, 14
Root canal biofilms, 22–24
growth and maturation, 25
initial adherence to surfaces, 23
secondary colonizers, 23
Root canal infections, 14, 15, 83, 90
chronic, 29
Enterococcus faecalis in, 25
health and, 3
Root canal perforations, 97
Root canal treatment
controversies of success and failures of, 46
time passed since primary, 46
Index
136
Root-filled tooth
cross-sectional studies reporting on, 10–11
extraction of, 117
frequency and prevalence of, 14
loss of, 16
pain from, 50
pulpitis in, 45
RPD. See Removable partial denture (RPD)
S
Single missing tooth replacement, 125–128
Single-rooted maxillary incisor, 83
Single-tooth gap, prosthodontic treatment, 119, 124
Single-tooth replacement, 118
Soft tissue management, 84
Streptococcus oralis, 29
Stress-regulator mechanism, 29
Strindberg system, 60
Stropko™ irrigation needle, 97
Surgical retreatment, apical periodontitis, 73–74
anatomical considerations, 78–82
biological considerations, 76–78
bleeding control during surgery, 84–85
indications, contraindications, and treatment
planning, 74
medical considerations, 82–83
postoperative information and complications, 85–86
prognosis, 86
root resection and retrograde treatment
of root canal, 85
soft tissue management, 84
suturing, 85
technical considerations, 74–76
Surgical/nonsurgical retreatment,
apical periodontitis, 66–67
accessibility to root canal, 67–68
costs, 68
preferences of clinician and patient, 68
restorative requirement of tooth, 68
size of bone destruction, 67
technical quality of previous treatment, 67
T
Temporomandibular disorder, referred pain from, 45
Tissue growth factors (TGF-β), 27
Tooth. See also specific types of tooth
loss of, 34
space assessment, 120
Trigeminal neuralgia, 45
U
Upper lateral incisor, 75
Upper right canine, 82
V
Vertical root fracture, 44