Reendodontic treatment
(possibilities apexlocators
in endodontic therapy)
Retreatment in endodontics
21ST-CENTURY ENDODONTICS
Endodontics as a discipline has offered
patients the opportunity to maintain their
natural teeth.
As the population expands and ages,
the demand for endodontic therapy can
be expected to increase as patients seek
dental options to keep their teeth for a
lifetime.
Retreatment in endodontics

Over the past decade, nickel titanium rotary
instrumentation,
microscopic
endodontics,
digital
radiography, a plethora of obturation systems, and
biocompatible
sealing
materials
have
helped
practitioners perform endodontic procedures more
effectively and efficiently than ever before.

Diagnosis, in fact, has become more challenging.
Overall, case management is more complex as geriatric
patients and those who are medically compromised are
more inclined to seek treatment to save their teeth.
Retreatment in endodontics

Endodontics has gone through many changes in the
past several years. Bacterial culturing of canals, the use
of silver points, multiple endodontic visits, radiographic
“guessing” of working lengths, and dependence on
canal medicaments are fading concepts in endodontic
treatment.

Thanks to modern techniques used in endodontics,
most of the teeth, which in the past would be removed
currently can be saved. Many patients have had bad
experiences associated with the "root canal therapy"
and in this context often face a dilemma: whether to
remove or cure? The latter approach is irreversible and
should be treated as a last resort. We tried to make the
treatment as light as possible, short and comfortable.
Retreatment in endodontics

A variety of advancements in technology,materials,
equipment, and even philosophy have changed how
endodontic cases are managed.

Electronic apex locators and surgical microscopes have
heightened precision and eliminated much of the
uncertainty associated with endodontic procedures.
Digital radiography has expanded diagnostic abilities
and increased the ability to communicate with patients
and other dentists.
Endodontic treatment consists of
 removing the contents of the chamber and
canal system-the pulp (a network of blood
vessels and nerves)
 the elimination of bacteria
 filling tightly root canals


For that we use:
 modern tools to process canals
 systems for their filling
 apex locator to measure the length of the
root
 dental RTG
 endodontics microscope
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Endodontic Services
Root Canal Therapy

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
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With Rotary System
With Apex Finder
Re-Endodontic Treatment
Apicectomy
Hemisection
Re-Implant Endodontic
Electronic apex locators
•Prior to root canal treatment at least one undistorted
radiograph is required to assess canal morphology.
The apical extent of instrumentation and the final root
filling have a role in treatment success, and are primarily
determined radiographically.
•Electronic apex locators reduce the number of
radiographs required and assist where radiographic
methods create difficulty.
They may also indicate cases where the apical
foramen is some distance from the radiographic apex.

The removal of all pulp tissue, necrotic material and
microorganisms from the root canal is essential for
endodontic success. This can only be achieved if the
length of the tooth and the root canal is determined with
accuracy. The outcome of treatment of roots with
necrotic pulps and periapical lesions is influenced
significantly by the apical level of the root filling

Traditionally, the point of termination for endodontic
instrumentation and obturation has been determined by
taking radiographs. The development of the electronic
apex locator has helped make the assessment of
working length more accurate and predictable .
The importance of working length
Grove (1930) stated that ‘the proper point to which
root canals should be filled is the junction of the dentin
and the cementum and that the pulp should be severed
at the point of its union with the periodontal membrane’.
The cementodentinal junction (CDJ) is the anatomical
and histological landmark where the periodontal ligament
begins and the pulp ends. Root canal preparation
techniques aim to make use of this potential natural barrier
between the contents of the canal and the apical tissues.

The importance of working length

It is generally accepted that the preparation and
obturation of the root canal should be at or short of the
apical constriction. An in vivo histological study found
that the most favourable histological conditions were
when the instrumentation and obturation remained short
of the apical constriction and that extruded gutta-percha
and sealer always caused a severe inflammatory
reaction despite the absence of pain .

The problem clinicians face is how to accurately identify
and prepare to this landmark – the ‘working length’ – and
achieve maximum success. Epidemiological studies
have reported that the best prognosis is when the root
filling lies within 2 mm of the radiographic apex (Sjo¨gren
et al. 1990). The variations in anatomy of tooth apices
both by age and tooth type make this task all the more
challenging.
Anatomy of the apical foramen


To appreciate fully the concept
of working length, an
understanding of apical
anatomy is required. The
anatomy of the apical foramen
changes with age.
Figure 1a shows a concept of
the apex (a), the apex of a
younger person (b) and the
changing apex due to hard
tissue deposition (c).
(a) Position of the apical foramen (adapted from
Kuttler 1955). (b) Anatomy of the root apex,
Anatomy of the apical foramen

It is generally agreed that there are three distinct aspects
of the apex that must be appreciated. Figure 1b shows
these as the tooth apex (1), the apical foramen [major
foramen (2)] and the apical constriction [minor foramen
(3)] which is also described as the CDJ.

The apical foramen is not always located at the
anatomical apex of the tooth. The foramen of the main
root canal may be located to one side of the anatomical
apex, sometimes at distances of up to 3 mm in50–98%
of roots Dummer et al. (1984) reported the mean apex to
foramen distance (Fig. 1b, 4) in anterior teeth to be 0.36
mm. The general trend is that the apex to foramen
distance is greater in posterior teeth and older teeth than
in anterior and younger teeth.
Anatomy of the apical foramen

The foramen to apical constriction (Fig 1(b)5) is
approximately 0.5 mm in the younger group and 0.8 mm
in the older group for all tooth types

Traditional methods for establishing working length have
been (a) the use of anatomical averages and knowledge
of anatomy, (b) tactile sensation, (c) moisture
on a
paper point and (d) radiography
.Radiographic determination of working length has been
used for many years. The radiographic apex is defined
as the anatomical end of the root as seen on the
radiograph, while the apical foramen is the region where
the canal leaves the root surface next to the periodontal
ligament (American Association of Endodontists 1984).

Anatomy of the apical foramen

When the apical foramen exits to the side of the root or
in a buccal or lingual direction it becomes difficult to view
on the radiograph.

The preoperative radiograph is essential in endodontics
to determine the anatomy of the root canal system, the
number and curvature of roots, the presence or absence
of disease, and to act as an initial guide for working
length. The electronic apex locator is an instrument,
which used with appropriate radiographs, allows for
much greater accuracy of working length control
Apexlocators

An electronic method for root length determination was
first investigated by Custer (1918).

Third generation apex locators are similar to the
second generation except that they use multiple
frequencies to determine the distance from the end of the
canal. These units have more powerful microprocessors
and are able to process the mathematical quotient and
algorithm calculations required to give accurate readings.

The relative values of frequency response method detects
the apical constriction by calculating the difference
between two direct potentials picked up by filters when a 1
kHz rectilinear wave is applied to the canal.
Apexlocators

Many of the problems with previous generations of apex
locators occurred when the root canal contained moisturerich substances such as exudate, electrolytes like sodium
hypochlorite and the products of hemorrhage. The new
third-generation apex locators have overcome most of
these problems, are more user-friendly and require
minimal calibration.

More importantly is the revelation that modern-day apex
locators may even be more reliable than radiographic
interpretation. Studies evaluating apex locators have
demonstrated accuracies of working length determination
to within 0.5 mm from the apical constriction, ranging from
75 percent to 93.4 percent. Nonetheless, using today’s
apex locator in conjunction with a radiograph is still an
extremely effective adjunct for determining working length
and detecting perforations or root fractures.
Apexlocators

Current apex locators utilize an alternating current within
the canal and monitor the impedance between periapical
tissue and oral mucosa via a lip clip. The circuitry within
the machine calculates the impedance between the file
tip and lip mucosa; the apex is detected using the
calculated impedance via needle pointers, sounds,
lights, digital reads or various combinations thereof
depending on the machine used.
Apexlocators
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New technology in this area has resulted in
microprocessors that measure frequency shifts and
apical capacitances.
As a result, accuracy of these locators has improved,
especially in the presence of anatomical aberrations and
canal moisture.
Examples of these include the Root ZX (J. Morita USA),
the Justwo (Medidenta International) and the Endex
(Osada Inc.). Some of these use an alternating current of
at least two frequencies, and measure and compare the
two electrical impedances.
Apexlocators
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This millennium is certain to deliver even more accurate
apex locators, perhaps even totally eliminating working
length images.
However, even if that goal is never attained, there are
obvious advantages with the third-generation apex
locators available today. These include an accurate
working length determination, thereby reducing overall
radiation exposure, as only a minimal number of images
would be required. With accurate readings, there may be
less chance for over- or underinstrumentation. Also,
patient treatment time would be reduced as the result of
the speed at which a length can be determined or
verified.
Apexlocators
Apexlocators
Apexlocators
Root Canals not suitable for Electronic Measurement
Reading (EMR)
Root Canal with a large apical foramen
Root canal that has an exceptionally large apical
foramen due to a lesion or incomplete
development cannot be accurately measured;
the results will show shorter measurement than
the actual length.
Root Canal with blood, saliva or a chemical
solution overflowing from the opening
If blood, saliva, or a chemical solution overflow from
the opening of the root canal and contacts the gums,
this will result in electrical leakage and an accurate
measurement cannot be obtained. Wait for bleeding
to stop completely. Clean the inside and opening of
the canal thoroughly to get rid of all blood, saliva
and chemical solutions and then make a
measurement.
Broken crown
If the crown is broken and a section of the
gingival tissue intrudes into the cavity
surrounding the canal opening, contact
between the gingival tissue and the file will result
in electrical leakage and an accurate
measurement cannot be obtained. In this case,
build up the tooth with a suitable material to
insulate the gingival tissue.
Fractured tooth
Leakage through a branch canal
Fractured tooth will cause electrical leakage and
an accurate measurement cannot be obtained.
A branch canal will also cause electrical leakage.
Re-treatment of a root filled with guttapercha
The gutta percha must be completely removed
to eliminate its insulating effect. After removing
the gutta percha, pass a small file all the way
through the apical foramen and then put a little
saline in the canal but do not let it overflow the
canal opening.
Crown or metal prosthesis touching
gingival tissue
Accurate measurement cannot be obtained if the
file touches a metal prosthesis that is touching
gingival tissue. In this case, widen the opening
at the top of the crown so that the file will not
touch the metal prosthesis before taking a
measurement.
Cutting debris on tooth
Pulp inside canal
Thoroughly remove all cutting debris on the
tooth.
Thoroughly remove all the pulp inside the canal;
otherwise an accurate measurement cannot be
made.
Caries touching the gums
In this case, electrical leakage through the
caries infected area to the gums will made it
impossible to make an accurate
measurement.
Blocked Canal
The meter will not move if the canal is
blocked.
Open the canal all the way to the apical
constriction to measure it.
Extremely dry canal
If the canal is extremely dry, the meter may not
move until it is quite close to the apex. In this
case, try moistening the canal
with oxydol or saline.
Retreatment in endodontics

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Retreatment in endodontics provides a second chance
for the patient to save the tooth that would otherwise be
deemed for extraction.
Treatment approach can be either surgical or non
surgical. Treatment failure can be due to many reasons
from missed canal to iatrogenic perforation which has to
be evaluated carefully before initiating the treatment.
Sometimes a clinician also has to deal with inter
appointment fl are ups requiring prompt and effi cient
patient management. This case report describes the non
surgical management of failed root fi lled teeth which had
also been treated surgically.
Conventional endodontic treatment may fail due to
various reasons and inadequate root canal treatment
with persistent infection remaining in inaccessible areas
of the canal being one of them
Fig 1: Clinical photo of
the patient showing
draining sinus
Fig 2: Preoperative
IOPA
Radiograph
Fig 3: After Gutta percha
removal
Fig 4: Immediate
post obturation
Fig 5: 12 months recall
Fig 6: 24 months recall
(decrease in
size of periapical lesion is
evident)
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If root fi lled tooth has failed, there can be fi ve possible
treatment options: To review or do nothing, root canal
retreatment, root end surgery, extraction followed by
implant or referral. Cross sectional studies from different
countries including most recent studies clearly
demonstrate that more than 30% of all root fi lled teeth in
the population are associated with apical periodontitis or
post treatment disease9,10,11,12. A general guideline
has
been
given
by
European
Society
of
Endodontology13 for indications of retreatment, they are;
• Teeth with inadequate root canal fi lling with
radiological fi ndings and/or symptoms
• Teeth with inadequate root canal fi lling when the
coronal restoration requires replacement
• Teeth with coronal dental tissue that is to be bleached
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Conclusion
There is enough potential for success of primary
root canal fi lling but fact remains that clinicians
are confronted with post treatment disease.
Endodontic retreatment could be a suitable
option in case of a post treatment disease
following an endodontic failure.
Nonsurgical procedures could look of minor
importance or insignifi cant during retreatment,
for managing surgical endodontic failure
especially when reendodontic surgery appears
inevitable. However, with non surgical treatment
approach and adequate apical and coronal
sealing we can achieve favourable clinical
outcome even in case of failed surgically treated
teeth.