Australian Dental Journal 2009; 54:(1 Suppl): S27–S43
doi: 10.1111/j.1834-7819.2009.01141.x
Radiographs in periodontal disease diagnosis and
management
EF Corbet,* DKL Ho,* SML Lai*
*Periodontology, Faculty of Dentistry, The University of Hong Kong.
ABSTRACT
Radiographs are an integral component of a periodontal assessment for those with clinical evidence of periodontal
destruction. A close consideration of the current approach to periodontal diagnosis compatible with the current
classification of periodontal diseases reveals that radiographs only inform with respect to diagnosis for a small proportion of
conditions. The area in periodontal assessment in which radiographs play a pivotal role is in treatment planning. A variety
of radiographic exposure types assist in the development of periodontal treatment plans. This ‘‘therapeutic yield’’ can be
achieved by panoramic oral radiographs supplemented by selective intra-oral views. Digital panoramic oral radiographs
viewed on screen appear to offer advantages over printouts or films. Newer imaging approaches, such as cone-beam
computed (digital volume) tomography, may come to show some usefulness but experience has shown that digital
subtraction radiography will probably remain a research tool without much clinical application.
Keywords: Radiographs, periodontitis, diagnosis, treatment, imaging.
Abbreviations and acronyms: CADIA = computer-assisted densitometric image analysis; CEJ = cemento-enamel junction; CT = computed
tomography; DSR = digital subtraction radiography; DVT = digital volume tomography; GTR = guided tissue regeneration.
INTRODUCTION
It is generally widely accepted that radiographs
supplement clinical examination in establishing the
diagnosis and guiding the treatment plan for a patient
affected by those periodontal diseases which have
contributed to destruction of the periodontal attachment. A range of findings of relevance to clinically
evident periodontal conditions can become apparent
on radiographs. Radiographs can provide key information of relevance to periodontal decision making
which is not capable of being captured by clinical
examination, such as length of root(s) with remaining
bony support.
Published reviews on radiographs and imaging in
periodontology this decade – 2000 onwards
There have been at least four previous reviews on
radiographs and imaging in periodontology since the
turn of this century. Each of these reviews has had a
different emphasis and each will be introduced briefly.
Each review rewards careful study and each has taken a
different approach to this topic.
ª 2009 Australian Dental Association
Tugnait and colleagues1 in 2000 reviewed the
usefulness of radiographs in diagnosis and management
of periodontal diseases. Their review aimed to cover
periodontally significant diagnostic information obtainable from conventional radiography and to consider
how, with respect to periodontal therapy, radiographs
may influence patient management. The studies
reviewed were selected on the basis of offering information on the role of radiographs in the diagnosis of
periodontal diseases and in guiding management of
periodontal diseases at various stages of treatment.
Furthermore, evidence for the value added by the
viewing of radiographs was critically reviewed. That
review concluded that various features of periodontal
diagnostic interest are apparent on radiographs, that
the visualization of these may be dependent on the
radiographic view chosen, that a relationship exists
between clinical attachment and radiographic bone
height, and that radiographs can be used in all stages of
periodontal care, although some decisions may be made
following clinical assessment only. That thought provoking review, however, noted that any evidence of the
benefit gained from radiographs taken for periodontal
patients was, up to the year 2000, sparse. Further, the
S27
EF Corbet et al.
literature reviewed poorly addressed the extent to
which radiographs influenced treatment decisions and
treatment outcomes. The authors concluded that clinicians should critically appraise the traditional role of
radiographs in the diagnosis and management of
periodontal disease to ensure that all radiographs do
indeed provide clearly defined benefits to patients.
Hausmann2 in 2000 reviewed radiographs and
digital imaging in periodontal practice. Hausmann’s
review first considered the terminologies ‘‘accuracy’’
and ‘‘reproducibility’’ in imaging, and covered how to
produce standardized X-radiographs and how to manage serial X-radiographs once these have been digitized.
Then he considered what alveolar bone height indicated
no bone loss, taken as 1.9 mm from the cementoenamel junction (CEJ) in molar sites on bitewing
radiographs3 and what cut-off can be used to indicate
a change in alveolar bone height, taken as 0.71 mm for
routine paralleling periapical radiographs.4 He noted
the correlation between the radiographic bone height
and clinical attachment level and then dealt with
methods of digital image subtraction and considered
what investigations such approaches may allow for. He
concluded his review optimistically by forecasting that
linear radiographic measurements of digitized and
computer managed images, rather than just visual
inspection of radiographs, will in the not-too-distant
future, measured from the year 2000, be commonplace
in the management of patients with periodontal diseases. He noted that subtraction radiography (being
able to tell differences in structures recorded between
one standardized digital or digitized radiograph and
another) could be of great use to the practising
periodontist.
Mol5 in 2004 extensively reviewed imaging methods
in periodontology covering why and when to use the
following imaging: intra-oral and extra-oral radiography, digital radiography, digital subtraction radiography, computed tomography (CT) and ‘‘new frontier’’
imaging including cone-beam CT. In considering
‘‘where do we go from here?’’, Mol notes that the
digital era is in its infancy but that current non-digital
approaches to handling radiographic images can be
improved upon, nonetheless concluding that there is
little doubt that periodontists of the future will be using
more advanced imaging modalities.
Tugnait and Carmichael6 in 2005 reviewed the use of
radiographs in the diagnosis of periodontal disease.
That review, written basically for general practitioners,
had as a focus the selection of radiographs following
clinical examination and taken only on the basis of
clinical findings, noting that each exposure should be
justified.
Bragger,7 also in 2005, reviewed radiographic
parameters, their biological significance and clinical
use. His review considered conventional versus digital
S28
imaging methods, the radiographic parameters obtainable in daily practice – linear measurements from
landmarks to alveolar bone crest and tooth and root
lengths, angular defects, defect angles, furcation radiolucencies – noting the influence of methodological
errors. Bragger considered the perception of biological
processes which can be derived from radiographic
images and dealt in some detail with the clinical use of
radiographs, reviewing the role that radiographs have
in establishing a periodontal diagnosis, creating a
treatment plan, estimating disease risk, and documenting tissue stability, breakdown or remodelling. He
noted that image processing, such as digital subtraction,
is a pure research tool, a different conclusion to that of
Hausmann.2
Thus, there is a series of recent reviews to which
readers of the Australian Dental Journal can refer in
building up a picture of the utilities of radiographs (and
newer imaging methods) in the diagnosis of periodontal
diseases and to some extent in the treatment of these
diseases. However, some questions remain, questions
raised directly in these recent reviews or issues not
themselves directly considered heretofore.
This review raises for consideration issues to do with
periodontal diagnosis, questioning the exact role of
radiographic imaging, covers the usefulness of panoramic radiography in periodontal assessment and in
treatment planning decision making, considers the
practicalities of digital imaging in periodontology,
shares experiences with digital subtraction radiography
and considers possible utilities of cone-beam computed
(digital volume) tomography in periodontology.
Radiographs in periodontal disease diagnosis
In this issue, Highfield8 has dealt with the current
situation regarding diagnosis based on the outcome of
an International Workshop for Classification of Periodontal Diseases.9 The word ‘‘diagnosis’’ is derived
through Latin from the two Greek words, romanized as
‘‘dia’’ meaning ‘‘to split’’ or ‘‘apart’’, and ‘‘gnosis’’
meaning ‘‘to learn’’. Thus, diagnosis really implies
being able to separate one (or more) conditions from
another (or others). In medicine this telling apart of
different departures from normal, or health, in a person
constitutes diagnosis. In Periodontology 2000, Armitage10 proposed that a ‘‘periodontal diagnosis’’ is a
‘‘label’’ which clinicians place on a person’s periodontal
condition or disease. This label given to a person’s
periodontal condition (if departing from what is
considered normal form for a given racial group) or
disease should conform, or be convertible, to current
classification of periodontal diseases (and conditions).
Highfield8 has provided a more convenient and simplified summary of the current classification. The use of
radiographs in arriving at the ‘‘label’’ to attach to a
ª 2009 Australian Dental Association
Radiographs for diagnosis and management
person’s periodontal condition or disease is considered
according to the structure given by Highfield.8
I. Gingival diseases11
Both A. Plaque induced, and B. Non-plaque induced,
gingival diseases can be diagnosed on the basis of
clinical findings, and the results of further investigations, without the need for radiographs. Also, there is
recognition in the 1999 classification that plaque
induced gingivitis may occur on a reduced periodontium which is not undergoing progressive destruction.11
It is possible, if clinical records (chartings and study
casts) are comprehensive and accurate, for stability of a
reduced periodontium to be assessed without the need
for radiographs, although radiographs should of course
reveal further alveolar bone loss, but such radiographic evidence would in normal clinical circumstances
only be a confirmatory finding of new or recurrent
periodontitis.
II. Chronic periodontitis12
Both A. Localized and B. Generalized chronic periodontitis are characterized by pocket formation and ⁄ or
gingival recession, both clinically detectable without
radiographs. Chronic periodontitis can be divided into
localized if less than 30 per cent of available sites
display clinical attachment loss, and generalized if more
than 30 per cent of sites display clinical attachment
loss. This differentiation is made on the basis of clinical
findings and so radiographs are not required, although
radiographs may be used but may mislead. Chronic
periodontitis can be further characterized by various
degrees of severity on the basis of measures of clinical
attachment loss. Therefore, for the assessment of the
severity of chronic periodontitis, radiographs are not
required although radiographs may be used, but are
not essential. The manner in which radiographs may
mislead in the assessment of extent is that the chronic
periodontitis may have been treated and while the
radiographs may show (and here because conventional
radiographs do not allow for an interpretation of
buccal and lingual sites and so only interproximal sites
can be assessed and calculated) the extent of the
number of interproximal sites, or teeth, with bone loss
however it is the presence or absence of the clinical
signs apparent only on clinical examination which
indicate extent of current chronic periodontitis. Similarly in the determination of the severity of chronic
periodontitis from the estimation of alveolar bone
heights shown on conventional radiographs, the
chronic periodontitis might have been previously successfully treated and so the assessment of severity is an
assessment of the severity of the previous chronic
periodontitis and not of the current status.
ª 2009 Australian Dental Association
The diagnosis of chronic periodontitis is made on the
basis of periodontal pockets and ⁄ or recession. In some
clinical situations restorations may impede the accessibility of the periodontal probe into a pocket and ⁄ or
may obscure the CEJ and so compromise the clinical
assessment of the presence and severity of chronic
periodontitis. In such a situation radiographic evidence
of alveolar bone loss may be helpful. Similarly,
subgingival calculus or root surface topographies or
malformations may impede the passage of the periodontal probe. In these situations radiographic evidence of alveolar bone loss may be helpful as it
may direct the attention of the examining clinician to
probe carefully sites or teeth with evident radiographic
bone loss.
III. Aggressive periodontitis13
Both A. Localized and B. Generalized aggressive
periodontitis share the common features of chronic
periodontitis, pockets and ⁄ or recession. However, there
is or has been rapid attachment loss and bone
destruction and, where possibly noted, a familial
aggregation can be elicited, and apart from the
periodontitis the patients are otherwise clinically
healthy. It was suggested13 that the diagnosis may be
based on clinical, radiographic and historical data,
although it can be questioned whether radiographs are
required for the diagnosis. The issue is that the
diagnosis of aggressive periodontitis can be made with
recourse to laboratory testing.13 The differentiation
between A. Localized: first molar ⁄ incisor presentation
with interproximal clinical attachment loss on at least
two permanent teeth, one of which is a molar and
involving no more than two teeth other than first
molars and incisors; and B. Generalized: interproximal
clinical attachment loss affecting at least three permanent teeth other than first molars and incisors, needs to
be made clinically and radiographs are not required.
The diagnosis ought not be made on the basis of
radiographs alone, and given that the key feature is
clinical attachment loss, radiographic examination is
not required for the diagnosis of aggressive periodontitis, although the localized form may present with
a very characteristic ‘‘mirror image’’ pattern of bone
destruction.
IV. Periodontitis as a manifestation of systemic disease
Highfield8 notes that this classification, periodontitis as
a manifestation of systemic disease, proposes only those
diseases in which the periodontitis is a manifestation of
the disease process and does not include disease states
or medications which modify existing periodontitis.
Periodontitis as a manifestation of a disease process can
be diagnosed and characterized on the basis of the
S29
EF Corbet et al.
findings from a clinical examination without the need
for radiographs.
V. Necrotizing periodontal diseases14
Necrotizing periodontal diseases are divided into A.
Necrotizing ulcerative gingivitis, an infection characterized by gingival necrosis presenting as ‘‘punchedout’’ papillae, with gingival bleeding and pain. A
characteristic foetid breath and pseudomembranes
covering the ulcerations, which themselves bleed readily on being disturbed, may be noted; and B. Necrotizing ulcerative periodontitis in which there is not only
necrosis of gingival tissues but also necrosis of periodontal ligament, and alveolar bone. Both of these
diagnoses are established on the basis of the symptoms
and the clinical signs, and radiographs are not required.
VI. Abscesses of periodontium15
Abscesses affecting periodontal tissues were divided
into: A. Gingival abscess, a localized prevalent infection
that involves the marginal gingiva or interdental
papilla; B. Periodontal abscess, a localized purulent
infection within the tissues adjacent to a periodontal
pocket; and C. Pericoronal abscess, a localized purulent
infection within the tissue surrounding the crown of a
partially erupted tooth. A periodontal abscess may lead
to the destruction of periodontal ligament and alveolar
bone whereas a gingival abscess and a pericoronal
abscess probably will not give rise to radiographically
detectable bone loss. Conventional radiographs may,
therefore, allow for the differentiation between a
gingival abscess and a periodontal abscess but clinical
findings alone should be sufficient to allow for this
differentiation. Highfield8 notes that periodontal
abscesses may result from root fractures or cemental
tears. Such misfortunes may not be apparent radiographically, but if detected on radiographic examination than the radiograph(s) can be said to have been an
aid in determining the underlying cause for the
diagnosed condition, but any radiograph(s) did not
serve, as is often implied, as an ‘‘aid to diagnosis’’,
because the diagnosis of a periodontal abscess was
made on the basis of the clinical findings.
VII. Periodontitis associated with endodontic lesions16
Simply reducing all categories of combined periodontalendodontic lesions, without any need to determine
which component preceded or were the cause or the
result of the other, is a pragmatic approach which has
been adopted for the diagnosis of lesions in which there
is any coalescence of endodontic and periodontal
pathologies. A primary periodontal lesion which mimics an endodontic lesion is still just solely a periodontal
S30
lesion and so is not a ‘‘perio-endo’’ lesion. Similarly, an
endodontic lesion with a sinus draining through the
periodontal ligament, which after successful endodontic
therapy completely resolves without the need for any
periodontal therapeutic intervention, is only an endodontic lesion and is not a ‘‘perio-endo’’ lesion. Hence,
all that needs to be diagnosed is a coalescence of
periodontal and endodontic pathologies and this is
termed a combined periodontal-endodontic lesion. For
this diagnosis the standard conventional intra-oral
radiographic exposures for diagnosing periapical periodontitis, usually periapical radiographs, are required,
and if periodontal pathology is evident clinically a longcone paralleling technique17 is preferred for the taking
of the periapical radiographs. The use of gutta-percha
cones inserted into any sinus opening to trace the origin
of a draining lesion is a very useful approach at the time
of exposing a paralleling periapical radiograph in the
diagnosis of combined lesions.
VIII.Developmentaloracquireddeformitiesandconditions
As Highfield8 notes, this category of the current
classifications seems to have been added for completeness. Another interpretation is that these seem to be
included in the classification because clinical periodontology devotes some time and energy to correcting, or
at least managing these, and if these were not included
in the classification then the justification for the
expenditure of clinical effort and the use of clinical
time could be questioned. It is only for tooth-related
conditions18 that there may be a periodontal diagnostic
imperative for radiographic examination.
Whether radiographs are required for the establishment of a diagnosis compatible with the current classification system (I to VIII) is summarized in Table 1.
Clinical assessment of the need for radiographic
examination in periodontal patients
The Australian Radiation Protection and Nuclear
Safety Agency’s Code of Practice for Radiation Protection in Dentistry19 and its Safety Guide for Radiation
Protection in Dentistry20 both make it abundantly clear
that there is a responsibility for clinical assessment for
the need for dental radiography to be performed, unless
an emergency situation dictates otherwise, and for this
to precede the radiographic exposure. Radiography
must not be a substitute for clinical investigation,
and routine use of X-radiographs as a component of
periodic examinations or at any given frequency cannot
be condoned. This code of practice and safety guide
presumably offer the most definitive available advice to
dentists in Australia on radiography in dentistry and the
advice should be heeded, specifically all the advice given
on minimizing exposure to ionizing radiation.
ª 2009 Australian Dental Association
Radiographs for diagnosis and management
Table 1. Radiographs in periodontal diagnosis
Diagnosis
Radiographs required for establishing diagnosis
Gingival diseases
Chronic periodontitis
Aggressive periodontitis
Periodontitis as a manifestation of periodontal diseases
Necrotizing periodontal diseases
Abscesses of the periodontium
Periodontitis associated with endodontic lesions
Developmental or acquired deformities and conditions
Not required
Not required
Not required but sequential radiographs may display rapid bone loss
Not required
Not required
Not required but may reveal cause
Required, as if for endodontic diagnosis
Required really only for some tooth related
Table 2. Clinical periodontal findings not captured on
radiographs
Table 3. Conventional radiography – findings relating
to predisposition to periodontal diseases
Gingival redness
Gingival swelling
Gingival bleeding
Gingival recession
Gingival enlargement
Bleeding on probing
Probing pocket depths
Tooth hypermobility
Suppuration
Calculus* – usually approximally
Overhanging radiopaque restorations* – usually approximally
Root anomalies ⁄ malformations
Root features
Cemental tears
Many of the clinically important features of periodontal diseases are not evident on radiographs
(Table 2), but nonetheless radiographic investigation
is only ever warranted after careful clinical examination and recording. In the event of clinical signs of
periodontitis, probing pocket depths and ⁄ or recession,
being encountered in a clinical examination, radiographic examination yields some information on:
evident bone levels; evident patterns of bone loss, even
or angular; tooth-root lengths, morphologies and
topographies; and importantly length of tooth-root
radiographically surrounded by alveolar bone. Clinical
attachment loss (probing pocket depth plus recession,
or probing depth from the detected CEJ to the pocket
depth when there is no recession) is the diagnostic
yardstick for periodontitis and also the calculating tool
for determining clinical severity of periodontitis, but
remaining tooth-root support is the major complementary estimation provided only by radiographic imaging,
which while not diagnostic, is of pivotal concern in
treatment planning decisions, in prognosis estimation,
and, in fact, in contributing hugely to the eventual
outcome, the retention of periodontitis affected teeth in
acceptable function for life.
Some findings which relate to a predisposition to
periodontal disease are only evident radiographically
(Table 3).
Diagnostic yield of radiographs in clinical
periodontology
Surprisingly, there is really only one published study
which has investigated what was called ‘‘diagnostic
yield’’21 in periodontology. This study involved clinical
ª 2009 Australian Dental Association
*Detectable clinically.
examination of 300 subjects, 55 of whom had previous
radiographs, and a first treatment plan was developed.
Then a full-mouth radiographic survey (paralleling
periapical and bitewing radiographs) was performed
and a second treatment plan was developed. The first
and second treatment plans were compared, and
‘‘diagnostic yield’’ was the term given to the difference
between the first and second treatment plans. From
what was proposed by Armitage,10 a periodontal
diagnosis is the label put on a person’s periodontal
disease or condition. This means that unless ‘‘hopeless
tooth ⁄ teeth’’ is a label, which is not put on a
periodontal condition in any event, then this study did
not investigate ‘‘diagnostic yield’’ but rather investigated the impact of radiographs on treatment planning
in clinical periodontology, which could perhaps be
better termed a ‘‘therapeutic yield’’. The major differences in treatment plans between the first and second
plans were to do with teeth to be extracted, and then
restorative, endodontic and prosthodontic treatment
decisions. It appears from this study that radiography in
clinical periodontology informs treatment planning
more than it does diagnosis and, apart from decisions
to do with extractions, the therapeutic yield lies in the
other aspects of treatment needs: endodontic, restorative and prosthodontic. Hence, in compliance with
Australian guidelines19,20 radiographic examination in
clinical periodontology is only justified if changes in
treatment plans from those treatment plans developed
on the basis of clinical examination supplemented by
any already available radiographs are anticipated.
Often radiographs are prescribed to confirm already
established treatment decisions, and while sometimes
this may be justified to form a basis for informed
consent for instance, confirmatory radiographs are not
usually to be condoned. If the clinical findings, for
S31
EF Corbet et al.
example, indicate that a tooth is hopeless due to
extreme and symptomatic hypermobility accompanied
by advanced loss of clinical attachment, a radiograph
exposed purely to document this assessment of the
tooth being hopeless, based as it is on the clinical
findings, is not justified. In reality, exposure of the
patient to additional radiation would only be warranted if the tooth could be salvaged following the
study of a radiograph. The clinical findings, if accurately recorded in a patient’s records are sufficient
documentation of the findings, and a ‘‘for the record
only’’ radiograph is not advised. Further, in prescribing
dental radiographs in Australia all the advice given19,20
should be followed. It has been proposed elsewhere that
failure to minimize the x-ray dose exposure through
the use of E-speed films and rectangular collimating
devices may constitute a medico-legal issue.22 Indeed,
the positioning device shown in Fig 1b is for a
cylindrical cone and not for a rectangular collimating
device. When manufacturers of positioning devices have
been specifically questioned on the lack of rectangular
positioning devices, the reply has been that rectangular
collimating devices are not popular, and thus there
would not be a demand among those who purchase
x-ray equipment. Certainly, in Sweden23 and England
and Wales,24 published reports have suggested the
(a)
manufacturers’ assessments to be correct, documenting
as they do that concern for minimizing radiation
exposure is not widespread. However, the situation in
Australia with respect to general and specialist dentists’
adherence to x-ray dose reduction practices is not
known at present. This would make a worthwhile study.
Radiographic features impacting upon treatment
decisions
There are many features to do with bone and teeth
evident on conventional radiographs, in addition to
those relating to caries, endodontic, restorative and
prosthodontic conditions, which can impact on periodontal treatment planning. These are listed in Table 4.
One ‘‘paper case’’ based study with and without
radiographs in periodontal diagnosis and treatment
planning25 showed that the availability of radiographs,
as in the earlier ‘‘diagnostic yield’’ study,21 resulted in
more extractions being planned. These two studies
strongly support the contention that radiographs
inform periodontal treatment planning by revealing
not what has been lost but what is remaining. What is
remaining can be viewed from two aspects: (1) what
clinical challenges remain, in terms, for instance, of
debriding sufficiently well the root surfaces of incompletely separated (fused) roots of molar teeth or teeth
with radiographically evident root grooves ⁄ flutings on
roots; and (2) how much length of root appears to
remain embedded in alveolar bone, which estimation is
allowed by radiographic examination and which is not
discernable from the clinical examination.
Conventional radiographic views to assist periodontal
treatment planning
Conventional bitewing radiographs
(b)
Horizontal bitewing radiographs, while useful for
approximal caries detection, are not so useful in
informing periodontal treatment and treatment planning if bone loss is in any way advanced. Vertical
bitewing radiographs, whereby the film is placed with
its long axis at 90º to the placement for horizontal
Table 4. Conventional radiography – findings of
periodontal interest impacting upon treatment
decisions
Fig 1. (a) Vertical (left) and horizontal (right) bitewing tab positions.
(b) Vertical bitewing film holder.
S32
Bone levels
Bone loss – even or angular patterns
Intra(infra) – bony defects
Root morphologies ⁄ topographies
Furcation radiolucencies
Endodontic lesions
Endodontic mishaps
Developmental anomalies
Root length and shape(s) remaining in bone
ª 2009 Australian Dental Association
Radiographs for diagnosis and management
Fig 2. A Kwikbite ⁄ Parobite positioning device for a rectangular
collimating device for both vertical and horizontal bitewing
radiograph exposures, inserted into a round cone positioning ring.
bitewing radiography, can be very helpful if clinically
there is nothing suggestive of any previous endodontic
therapy or current periapical periodontitis alone or in
combination with periodontal destruction. The vertical
bitewing radiograph can be facilitated by placing the
‘‘tab’’ on which the patient bites at 90º to its position
for horizontal bitewings (Fig 1a), or by using a vertical
bitewing holder (Fig 1b) through which, if there is a
cone positioning ring, a reasonable degree of reproducibility can be achieved for subsequent sequential
radiographs. There is one Swiss product called the
Hawe Paro-Bite Centring Device which can be inserted
into a round positioning device which assists in
the positioning of rectangular cones for vertical and
horizontal bitewings (Fig 2). The assistance provided by
such a positioning aid is advised to reduce the need for
repeat radiographs and hence the need for unnecessary
x-ray exposure.
For intact arches, probably two vertical bitewing
radiographs per posterior sextant are required. Figure 3
shows one vertical bitewing with bone levels and
defects apparent revealing root morphologies of roots
in need of debridement. Not all root apices are evident
and hence some periapical bone is not visible.
Conventional periapical radiographs
Periapical radiographs when exposed for periodontal
purposes should use long-cone paralleling projections,
preferably with rectangular collimators. Full-mouth
surveys of paralleling periapical radiographs have been
considered to be a ‘‘gold standard’’ for periodontal
diagnosis and treatment planning. For some this view
still persists. For instance, the European Federation of
Periodontology still calls for this full-mouth series of
periapical radiographs in case presentations by candidates at the conclusion of higher education and training
in periodontology. However, there is no basis for
considering a full-mouth series of paralleling periapical
ª 2009 Australian Dental Association
Fig 3. A vertical bitewing, with bone levels and intrabony defects
apparent.
radiographs to influence periodontal treatment decisions any more than, say, panoramic radiographs.
The pictorial heading banner of the website* of the
Australian and New Zealand Academy of Periodontology shows a gloved hand holding a panoramic radiograph. If a panoramic radiograph is available, having
been exposed for whatever purpose, that radiograph
may alone be sufficient,26 or a panoramic radiograph
may be supplemented by selected intra-oral radiographs
which numbered less than four per patient to reach the
‘‘gold standard’’ in one study.27 It has been shown that
if seven periapical radiographs supplement a panoramic
oral radiograph then the effective radiation dose
exceeds that of a full-mouth series of periapicals,28
but if the number is less than four, then there is a
reduction in radiation exposure and yet the ‘‘gold
standard’’ in terms of information can be achieved.
Conventional panoramic oral radiographs
Modern panoramic oral radiography achieves decent
images suitable, with perhaps only modest intra-oral
supplementation, for periodontal treatment planning
purposes. The differences in any ‘‘yield’’, even with an
older generation of panoramic radiograph machines
*URL: ‘http://anzap.org.au’. Accessed 20 March 2009.
S33
EF Corbet et al.
and technology, in comparison with periapicals,29 and
bitewings,30 and bitewings and periapicals,31 and
periapicals and clinical probing32 were small, and for
newer panoramic radiograph technologies difference in
any ‘‘yield’’ are apparently even smaller.33 Panoramic
radiography in a group of periodontal maintenance
patients, that is patients previously affected by periodontal disease which had been treated and who were
undergoing supportive periodontal care, showed ‘‘great
agreement’’ with long cone intra-oral radiographs.34
Two of the recent reviews1,6 have dealt with the issue of
paralleling periapical series versus panoramic oral
radiographs. The features of interest for periodontal
assessment noted on periapical radiographs are also
capable of being noted on panoramic radiographs
(Table 5). For many practitioners the radiographic
features of interest on a panoramic, supplemented
where necessary by a small number of intra-oral views,
is sufficient for the management of periodontal diseases.
Tugnait and Camichael6 note how there has been a
pragmatic shift by many towards panoramic radiographs in the investigation of patients with periodontal
diseases, in view of time efficiency, greater patient
tolerance, and often a lower radiation exposure. Cost
savings are also more and more an issue, and while the
machinery for panoramic oral radiography is not
cheap, it is nowadays relatively cheaper than formerly,
and the time taken for producing a full-mouth periapical series is a costly investment if there is little by way of
yield.
The American Academy of Periodontology (AAP) in
its 2000 Parameter on Comprehensive Periodontal
Examination35 holds that ‘‘radiographs that are current, based on the diagnostic needs of the patient,
Table 5 (after Tugnait et al.1). Detectable features of
interest on radiographs
Bone levels
Bone loss
– even
– angular
Furcation involvement
Calculus
Radio-opaque restorative margins
– deficiency
– overhang
Root morphologies
Root length embedded in alveolar bone
Widened periodontal ligament space
Approximal root caries
Root canal fillings
Periapical periodontitis, cysts, granulomas
Impacted third molars
Retained roots
Fractured roots
Cemental tears
Cysts ⁄ tumours
S34
Periapical
Panoramic
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Often
Sometimes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Sometimes
Yes
should be utilized for proper evaluation and interpretation of the status of the periodontium … Radiographs
of diagnostic quality are necessary for these purposes’’.
It further states ‘‘Radiographic abnormalities should be
noted’’.35 Panoramic radiographs fulfil these conditions
(Table 5) and allow for the identification of radiographic abnormalities. The point made by the AAP that
there should be some record made of what was detected
on the radiographs is advice given in many jurisdictions. While available, the radiograph(s) reveal all that
can be discerned, but if the radiograph(s) is(are) not
available for whatever reason, then having some
written record of the findings should obviate the need
for any additional repeat radiograph to compensate for
the temporary unavailability of the radiograph(s). The
AAP in its 2001 Position Paper on ‘‘Guidelines for
periodontal therapy’’36 holds that ‘‘interpretation of a
satisfactory number of updated, diagnostic quality
periapical and bitewing radiographs or other diagnostic
imaging needed for implant therapy’’ is required. The
AAP contends that intra-oral radiographs, such as
periapical films and vertical or horizontal bitewings,
provide a considerable amount of information about
the periodontium that cannot be obtained by any other
non-invasive means.37 Panoramic radiographs certainly
do provide a considerable amount of information
(Table 5) and they also inform on treatment planning.
The situation of the AAP becomes clear on viewing the
AAP website* (‘‘Search Our Site’’: ‘‘Panoramic’’ in the
gateway to ‘‘Members Only’’ AAP Insurance Policy
Statement – Radiographs in Periodontics), where it is
stated: ‘‘The American Academy of Periodontology
believes that panoramic radiographs have limited value
in the diagnosis of periodontal disease …’’ This,
however, is only a ‘‘belief’’. A casual view of the world
reveals that not all share the same beliefs. The authors
of this review do not share the same belief as the AAP.
The expense, time and physical inconvenience in having
all periodontitis patients subjected to a full-mouth
series of periapical and bitewing radiographs on the
basis of a belief can be questioned, as it is in this review.
The American Board of Orthodontics is more reasonable in its advice, only requiring six intra-oral radiographs to supplement a panoramic view for adults for
comparison of pre-treatment and post-treatment crestal
bone levels and root status.38 One earlier study shows
how dearly belief systems with respect to full-mouth
periapical surveys can be held.39 In this American
study, the proportion of patients who had the results
from a screening clinical examination and a panoramic
radiograph but who were still judged by independent
examiners to be in need of full-mouth periapical series
was the same as for those patients who only had the
*URL: ‘http://www.perio.org/index_pro.html.’ Accessed 20 March
2009.
ª 2009 Australian Dental Association
Radiographs for diagnosis and management
clinical screening results. In that study, patients were
slated by the examiners for the full-mouth series of
periapical radiographs on the basis of the case type into
which they fell. Recommendations for the full-mouth
periapical radiograph series was made on the basis of
case type, and information available from the panoramic was not used because in the examiners’ opinions
that particular case type demanded the full-mouth
periapical series, because it seems that was what they
had been taught. When dental teaching hospitals in the
United Kingdom and Ireland were surveyed,40 the most
commonly taken views to assess periodontal status
were panoramic radiographs with selected periapical
radiographs. Hopefully, graduates from these dental
schools will follow their teaching, while constantly
evaluating the state of knowledge and experience in this
field and being prepared to change practice as new
evidence emerges.
Further, panoramic radiographs have been shown to
reveal in a majority (63 per cent) of periodontal
patients some form of dental abnormality unrelated to
periodontal disease.41 General radiologists in Australasia have had recent advice on the interpretation of
dental panoramic radiographs42 and should thus be
available for consultation, as would be other dental
specialists in Australia, if abnormalities detected were
to be out of the ordinary.
Panoramic radiographs may not reveal alveolar bony
defects as accurately as periapical radiographs.43,44
However, that is not the issue. The issue must be
whether there is any additional therapeutic yield from
any greater accuracy in representation of alveolar bone
destruction revealed on periapical radiographs.
A small study was conducted in Hong Kong in which
part-time clinical dental teachers were asked to develop
periodontal treatment plans on the basis of, in the first
instance, a complete periodontal charting, study casts
and a panoramic radiograph. The 35 patient records
chosen were of adult patients with, what would now be
diagnosed as, chronic periodontitis and who had at
least six teeth per quadrant. After a one-year wash-out
period, the same clinical records camouflaged, and
study casts were given along with, on this second
occasion, not the panoramic radiograph but a fullmouth series of paralleling periapical radiographs
which at the time of the charting had been prescribed
by a dental surgeon in the clinic in compliance with his
previous teaching. The individual treatment plans
derived on the first and second occasion were almost
identical. Between examiners there was variation in
treatment plans regarding periodontal surgery, as has
been reported from elsewhere,45 and extractions.
However, each individual part-time clinical dental
teacher developed almost identical treatment plans
from clinical findings and panoramic radiographs (of
an earlier generation) as they did from the clinical
findings and the full-mouth paralleling periapical
radiograph series. Hence, there was no perceptible
‘‘therapeutic yield’’ from the additional full-mouth
periapical radiograph series, such as that shown in
Fig 4.
The full-mouth series of periapical radiographs
shown in Fig 4 is mounted on a clear, not a traditionally
black, background. The Australian Safety Guide for
Radiation Protection in Dentistry20 suggests mounting
radiographs on a ‘‘mask’’ which eliminates stray light
around the radiograph, and provision for magnification
is also suggested as being advisable. The periapical
radiographs in Fig 4 are mounted on a clear background because each radiograph should be viewed
against a light-box using a viewing box with in-built
magnifying lens (Fig 5). Such viewing boxes are
available and are highly recommended not only for
conventional periapical and bitewing radiographs, but
also for the study of conventional panoramic oral
radiographs in assessing crestal bone loss and alveolar
bony defects.
While panoramic radiography may be less accurate in
the representation of bony defects than intra-oral
radiography,43,44 this has little therapeutic effect in
practice. For instance, many therapeutic decisions
to do with the management of bony defects are not
Fig 4. A full-mouth periapical radiograph series.
ª 2009 Australian Dental Association
S35
EF Corbet et al.
Fig 5. A radiograph viewing box to provide magnification and
to block out ambient light in use.
determined by the radiographic appearance, but rather
by the intra-operative appearance of the tooth-roots
and the bony defects. Guided tissue regeneration
(GTR), it has been concluded in a systematic review,46
achieves 1.22 mm more gain in clinical attachment
level at pocket sites than open flap (access flap)
debridement. Narrow and deep infrabony defects have
been shown to respond radiographically and, to some
extent at least, clinically more favourably to GTR than
wide and shallow defects, and depth was more indicative of favourable response than the angle of the
defect.47 This finding was confirmed in a follow-up
study.48 GTR requires a surgical approach to the
defects. The surgical approach allows for direct intraoperative assessment of defect depths and angles. No
reliance should be made on the radiographic assessment
of the bony defect. The most that the radiographic
assessment of defect depth and width might indicate
would be a preparedness to consider GTR as a
therapeutic alternative. The findings with respect to
the defect on flap reflection – whether the defect is
contained or circumferential, indeed whether the tooth
is treatable and retainable or not – determine the
S36
applicability of the GTR approach. This is decided
intra-operatively and not on the basis of the radiographic assessment alone, if indeed at all.
In a systematic review,49 Emdogain (an enamel
matrix derivative) was found to have improved probing
attachment levels by 1.2 mm and probing pocket depth
reduction by 0.8 mm compared to open (access) flap
debridement, although these results have to be interpreted with caution. The effectiveness of Emdogain is
also dependent to an extent on defect depth and defect
morphology. Emdogain has been shown to be very
successful, over a nine-year period, in deep defects50
and in angular defects.51,52 The depth of defect and its
suitability for Emdogain regeneration are all made
intra-operatively. Questions of interest to the operator –
such as ‘‘is the defect a deep defect?’’, ‘‘is it contained
or circumferential?’’, ‘‘are the root surfaces amenable
to debridement?’’ – can all be answered on the basis of
the intra-operative direct assessment. The pre-surgical
radiographic assessment again may only indicate that
Emdogain might be considered in the surgical treatment of that defect. Also, for Emdogain regenerative
therapy, as for GTR, often in the clinical situation on
surgical reflection of flaps, defects reveal themselves
to be topographically well suited to regenerative
approaches, when the pre-surgical radiographic assessment had not suggested such. In these clinical circumstances, the radiographic assessment has not guided the
eventual treatment approach adopted.
If an adjunctive regenerative approach had proved to
work with non-surgical periodontal therapy for specific
infrabony defect depths and configurations, but not for
others, then pre-treatment radiographic accuracy in
representing defects would be at a premium. Sadly,
however, Emdogain has been shown to offer no
advantage when applied as an adjunct to non-surgical
periodontal therapy.53–55 Hence for most therapeutic
decisions, and thus offering satisfactory ‘‘therapeutic
yield’’, panoramic oral radiography is, notwithstanding
its less accurate depiction of radiographically evident
alveolar bone defects, of great therapeutic use.
Digital panoramic radiography versus conventional
film panoramic radiography
There has, up to the present, been very little direct
comparison between digital panoramic radiographs and
conventional film panoramic radiographs in periodontal assessment. One study compared the efficacy of the
Orthophos DS Digital panoramic system with conventional film obtained from the Orthophos Plus (both
Sirona, Bensheim, Germany) and found that the
conventional film outperformed the digital panoramic
in the detection of periodontal findings.56 However,
based on a couple of years practical experience of
using digital panoramic oral radiographs, the authors’
ª 2009 Australian Dental Association
Radiographs for diagnosis and management
(a)
(b)
Fig 6. (a) Digital panoramic. (b) Zoomed-in portion of lower
left posterior sextant.
experience is that there is an advantage in periodontal
assessment. The digital panoramic system with which
the authors have experience uses a Kodak 8000C
Digital Panoramic Machine (from Kodak-Trophy,
Croissy-Beaubourg, France) using Kodak Dental Software, to feed into a patient database held on Trophy
DICOM software which is transferred into the hospital’s patient management system. An example of a
digital panoramic is given in Fig 6a and a ‘‘zoomed-in’’
portion of that image is shown in Fig 6b. The ability to
manipulate the panoramic images, such as zooming in
and changing contrast, has proved a very useful feature
in assessment of bony defects and root morphologies,
and open (access) flap debridement surgeries have
confirmed an impression of a greater ability in anticipating the shape, depth and extent of bony defects
following study of digital panoramic radiographs
compared to viewing conventional panoramic oral
radiographs. The ability to zoom in and magnify
defects and to adjust dynamically the contrast and
brightness allows for vastly improved ‘‘visualization’’
of bone levels and intra-bony defects. To date one study
has shown that periapical periodontitis was more
scoreable on screen from digital panoramic radiographs
than on printed digital panoramic radiographs, supporting the advantages gained from manipulating the
digital panoramic oral images in assessing bony lesions
rather than interpreting only one static panoramic oral
image.57
ª 2009 Australian Dental Association
Digital intra-oral radiography
The authors’ experience with digital intra-oral radiograph for periodontal assessment is somewhat less
encouraging but nonetheless generally positive. There
are two approaches to digital imaging, direct digital
imaging and indirect digital imaging. ‘‘Direct’’ is
achieved by using a solid state sensor to detect x-rays.
For intra-oral use these sensors are bulky and inflexible,
and require a cable connection. These sensors must
convert x-ray detection to electronic signals for
subsequent electronic processing to produce usable
images. These direct digital images can be of high
quality. Readers are referred to earlier reviews2,5 for the
further information on direct digital imaging in periodontal assessment. Since these reviews2,5 have been
published, there has been not much change to the
conclusion that alveolar bone measurements are reproducible, using both direct digital and conventional
radiographs, and that direct digital radiographs do not
enhance examiner agreement over conventional radiographs.58 Of course digital images, derived from direct
digital imaging, or indeed also indirectly derived, can be
studied using image analyser tools. A study of one such
tool concluded that a dental image analyser tool can
reliably replace conventional measuring on intra-oral
film radiographs for measuring bone in periodontitis
patients.59 Such image analyser tools may well become
more of mainstream devices for quantifying bone loss,
and also post-periodontal therapy bone gain or bone
level stability.
Indirect digital imaging involves a latent image being
acquired using a photostimulable phosphor plate, and
then after the latent image is captured on this plate the
image is scanned by laser to produce a usable image.
The scanning process either erases the latent image on
the plate so that the plate can be reused straight away
without there being double imaging, or else the image
on the plate is only degraded by laser scanning and
must be erased by exposure to light. There are various
advantages of indirect digital imaging over direct digital
imaging. The plates can be the same sizes as intra-oral
conventional x-ray films and so all conventional intraoral clinical approaches can be used. Also there is
no need for a cable, patient tolerance is greater, and
the expense is less. However, there are disadvantages.
Depending on the approach, the image quality may not
be as good as with the direct imaging. Direct imaging
produces immediate images which is not necessarily so
with indirect digital imaging. Further, the flexibility of
the plate means that image distortion due to plate
bending can occur, as with film bending in conventional
radiography. If the plates are scratched, effectively they
are ruined, and so plates must be treated with great care
at all times. However, many other dental schools using
the same hospital patient management system as used in
S37
EF Corbet et al.
Hong Kong, into which indirect digital images are fed,
report very high quality images with great utilities.
Some studies on marginal alveolar bone levels do
confirm that indirect digital images had favourable
measurement accuracy compared with film radiographs,60 while colourizing digital images using colour-coding algorithms did not produce greater accuracy
in this respect.61 However, indirect digital bitewings
have been shown to be no better than film bitewings in
the assessment of alveolar bone loss.62 If decent images
are produced from indirect digital imaging, there is
no evidence to suggest that indirect digital intra-oral
radiographs are inferior to conventional intra-oral
radiographs in periodontal assessment and treatment
planning.
There is another approach to the management of
radiographs, sometime erroneously also referred to as
indirect digital imaging, and that is the digitization of
exposed and processed conventional x-radiograph films
using a flatbed scanner with a transparency adaptor.
This is the approach used to date in the digital
subtraction radiography (DSR) approach, considered
below. The viewing possibilities, e.g., projection of
such images, may improve interpretation,63 and such
subsequent management of conventional intra-oral
radiographs may facilitate the interpretation of periodontal bone defects,64 and of course image analysis
tools can be used on these digitized radiographs.
be made and attached to the film holders and the film
holder must be reproducibly aligned to the x-ray beam
collimating device (Fig 7). Once standardized serial
periapical radiographs have been produced, these
conventional radiographs must then be digitized using
flatbed scanning devices. Obviously, this step can be
omitted if direct or indirect digital images have been
collected. Then there are various methods to determine the changes (+ indicating more bone ⁄ more bone
density, – indicating less bone ⁄ less bone density)
between two radiographic images. Reference aluminium wedges can be captured in the images which more
easily allow for determination of density correction.65
Computer-assisted densitometric image analysis
(CADIA)66 of the digitized standardized intra-oral
radiographs is the method with which the authors have
experience.
A DSR system was developed at The University of
Hong Kong which has been calibrated and validated.67
This DSR system has been used in a published study on
a low-power laser system in periodontal therapy.68 It
has also been used in clinical studies on comparing
periodontal surgical therapy with repeated non-surgical
Digital subtraction radiography
Digital subtraction radiography (DSR) in periodontology basically allows the detection of small changes in
alveolar bone, which might otherwise go undetected.
For DSR to permit this to be realized, serial radiographs
need to be taken with the best possible reproducible
projection geometry and using standardized image
processing. To optimize the projection geometry custom (patient-by-patient, area-by-area) bite blocks must
Fig 7. A custom positioned periapical film holder with bite block
attached to a collimating device for digital subtraction radiography.
S38
Fig 8. Cone-beam Computed Tomography Machine (i-CAT,
Imaging Sciences International, Hatfield, USA).
ª 2009 Australian Dental Association
Radiographs for diagnosis and management
therapy, and on non-surgical therapy on post-menopausal females, comparing those taking with those not
taking hormone replacement therapy. Thus, quite some
experience with this approach has been gleaned. The
conclusion would be in line with that of Bragger7 that
DSR remains primarily a research tool for clinical trials.
Mol5 discusses how it is often proposed that the time
and effort involved in producing subtraction images of
high quality to detect small changes is prohibitive in
clinical practice. There are more issues to be considered. The storage of multiple custom bite blocks and
holders is a very practical one. The time taken in the
alignment of images prior to the CADIA is another.
Slight variations in choice of the regions of interest are
capable of producing contrary results. Also, if DSR
detects a loss of bone density or volume, but clinically
at that site there are no signs of gingival inflammation,
no bleeding on probing and no probing pocket depth,
then the reaction can be ‘‘so what?’’, because there is
nothing in the routine clinical periodontal armamentarium which can be applied at such a site. Mol5 opines
that at one level or another a price has to be paid for
increased diagnostic utility. But when the DSR ‘‘diagnosis’’ does not suggest any clinically useful intervention, then not only the ‘‘price’’ but the ‘‘utility’’ can also
be questioned. A further issue is what sites to select.
Studies can focus on specific sites, such as furcations69
and can show favourable outcomes to therapy in terms
of bone behaviour. A recent study of scaling and root
planing had 13 subjects but each subject had only three
sites included in the study.70 It can be questioned what
is special or representative about the sites chosen. The
DSR did reveal favourable outcomes to scaling and
rooting planing, but studies on scaling and root planing
have shown favourable effects on bone detectable
by conventional radiography. DSR was used in the
published study on low-power laser as an adjunct in
periodontal therapy.68 It showed a biological and
measurable early effect on bone, which could not be
detected by clinical means, but again the question
suggested is ‘‘so what?’’ as no clinically detectable
benefit could be observed.
A final issue in DSR is that periodontally involved
teeth are often mobile and can be displaced by the bite
block and ⁄ or the process of registering the bite prior to
therapy, but such teeth can firm up, and for drifted
teeth they may reposition themselves, in response to
therapy. Then the custom bite block does not fit posttherapy and the serial images cannot be aligned and the
altered tooth positions in the serial images cannot be
corrected for. The American Academy of Periodontology Position Paper on Diagnosis of Periodontal
Diseases37 very optimistically holds that future development of subtraction radiography techniques promises
Fig 9. i-CAT Vision software interface, consisting of pan-map (upper right), horizontal section (upper left), vertical sections (lower right)
and reconstructed 3-dimensional model (lower left).
ª 2009 Australian Dental Association
S39
EF Corbet et al.
to have a profound impact on the diagnosis of
periodontal diseases. The authors of this review could
not in any way agree.
Cone-beam computed tomography
Computed tomography (CT) has been used in some
studies in relation to periodontal defects.71,72 However,
conventional CT does not offer any favourable costbenefit, dose exposure or therapeutic yield advantage in
periodontal practice and is unlikely to find a routine
place.
Fig 10. Horizontal views of periodontal alveolar bony defects at upper
left second premolar (25) to upper left second molar (27).
Cone-beam geometry allows for reduced dose of
radiation. This, in combination with ‘‘fast’’ receptors
and the reduced cost of manufacturing the machines,
has allowed for the introduction of cone-beam CT into
dental ⁄ oral imaging. One difference between conebeam CT and conventional CT is that the cone-beam
produces increased scatter on images making conebeam CT unsuitable for soft tissue, a major benefit of
conventional CT, which in fact is an advantage in
dental ⁄ oral radiography wherein only radio-opaque
structures are generally studied. Machines specifically
for dental ⁄ oral use have been brought to the market
and are hugely impacting the field of dental ⁄ oral
imaging. Figure 8 shows one such machine, which
while less obtrusive than a medical CT machine, still
requires space to accommodate it. However, it seems
unlikely that these machines will soon become routine
in general dental practices. Because the cone-beam
geometry allows for a large volume of tissues to be
scanned with a single sweep resulting in a digital image,
cone-beam CT is also known in some quarters as digital
volume tomography (DVT).
Cone-beam CT for assessment of periodontal defects
has been applied in in vitro studies.73–77 These have all
suggested that there ought to be an application for conebeam CT in vivo in the imaging of periodontal defects.
There has, so far, been only one clinical report, of 12
patients, which suggests that cone-beam CT may provide
detailed information about furcation involvements in
patients with chronic periodontitis78 and so may influence treatment planning decisions. Obviously more
research is required. A preliminary study is underway
in Hong Kong on the utility of cone-beam CT in
periodontal assessment and in informing treatment
planning decisions in periodontitis patients. It takes
longer for general dentists, periodontology trainees and
Fig 11. Vertical views showing lingual furcation involvement at lower left first molar (36) and an extensive defect at palatal aspect of the upper left
first molar (26).
S40
ª 2009 Australian Dental Association
Radiographs for diagnosis and management
periodontists to come to decisions on the basis of
studying cone-beam CT images than full-mouth paralleling periapical radiographs. This is self-evident as the
cone-beam CT allows for bony defects and the root
surfaces within the defects to be studies from different
sectional views. Figure 9 shows the software interface of
one type of cone-beam CT management software (the
i-CAT Vision, Imaging Sciences International, Hatfield,
PA, USA). The interface consists of four windows. The
upper left window is the horizontal view of the arch and
the lower right window is a series of the vertical views of a
bony defect area. The lower left windows is the threedimensional stimulated reconstruction model of the
region of interest. Operators of the viewing software
can adjust the focal trough in the horizontal view shown
in the upper left image, along the form of the arch in this
window so that the pan-map image on the upper right
window can be constructed according to this trough. The
horizontal and vertical location bars can be adjusted to
centre on the defect of interest in the other two windows.
Figures 10 and 11 are the zoomed-in images of the
periodontal defects centred in Fig 9. Figures 10 and 11
show how the three-dimensional appreciation of the
defect and the tooth-roots can be elaborated. Operators
can adjust the position of the image, power of zoom-in
and zoom-out and contrast of the images in order to
assess a particular region of interest. The thickness of the
slices across an area of interest can also be adjusted down
to an interval of 0.2 mm.
These features of the software allow for an appreciation of the three-dimensional nature of defects to be
built up, for the root morphologies and topographies to
be studied, for buccal and lingual bony landmarks to be
discerned, which is not possible in conventional radiography. This is more time consuming than just viewing
periapical radiographs. The software to view the conebeam CT images has proved to be user friendly and
easily mastered by computer savvy dentists. Also, the
ability to take and manage good cone-beam CT images
has been easily acquired. How useful cone-beam CT
will prove itself in informing periodontal treatment
decisions still has to be determined. In the era in which
additional periodontal therapeutic approaches are
combined with surgical access to the periodontal
defects, intra-operative assessment will remain paramount, no matter how much further information is
available from advanced imaging techniques.
CONCLUSIONS
Radiographs do not play a major role in periodontal
diagnosis but are hugely useful in guiding periodontal
treatment planning decisions. The possible therapeutic
yield of any radiograph in periodontitis affected patients
must be considered before exposing patients to radiation to produce the radiographs. Radiographs, except in
ª 2009 Australian Dental Association
emergency situations, should be prescribed only on the
basis of a clinical assessment. Available radiographs can
all inform, and further radiographs should only be
considered in the light of clinical findings and the
information gained from the study of available radiographs. Vertical bitewing radiographs are of practical
use in periodontitis affected patients. Contemporary
panoramic oral radiographs can reveal what can be
detected on the basis of periapical radiographs, and a
refusal to acknowledge this has more to do with beliefs
than any evidence. Panoramic oral radiographs, supplemented by a limited number of selected intra-oral views,
selected on the basis of the clinical findings and the
appearance of the panoramic oral radiograph, can reach
the ‘‘gold standard’’ with reduced radiation exposure.
There is much research still to be performed on the
therapeutic yield of additional radiographs. Digital
panoramic oral radiographs, viewed through computers, seem to offer advantages over conventional film
panoramic radiographs and printouts of digitally
acquired panoramic radiographs. The loss in accuracy
in panoramic oral radiographs compared to periapical
radiographs in the depiction of alveolar bone defects
may have little impact on treatment planning decisions,
if these decisions need in the final analysis at the time of
open (access) flap surgical periodontal therapy, such as
the incorporation of regenerative approaches. Digital
and digitized radiographs allow for the use of image
analysis and measurement approaches, but how useful
these prove themselves to be is at present unknown.
Digital subtraction radiography will likely remain a
research tool. The application of cone-beam CT in
informing periodontal treatment decisions is only
beginning to be investigated, and its application and
utility remain to be elucidated.
REFERENCES
1. Tugnait A, Clerehugh V, Hirschmann PN. The usefulness of
radiographs in diagnosis and management of periodontal diseases: a review. J Dent 2000;28:219–226.
2. Hausmann E. Radiographic and digital imaging in periodontal
practice. J Periodontol 2000;71:497–503.
3. Hausmann E, Allen K, Clerehugh V. What alveolar crest level
on a bite-wing radiograph represents bone loss? J Periodontol
1991;62:570–572.
4. Hausmann E, Allen K. Reproducibility of bone height measurements made on serial radiographs. J Periodontol 1997;68:839–
841.
5. Mol A. Imaging methods in periodontology. Periodontol 2000
2004;34:34–48.
6. Tugnait A, Carmichael F. Use of radiographs in the diagnosis of
periodontal disease. Dent Update 2005;32:536–538; 541–532.
7. Bragger U. Radiographic parameters: biological significance and
clinical use. Periodontol 2000 2005;39:73–90.
8. Highfield J. Diagnosis and classification of periodontal disease.
Aust Dent J 2009;54(1 Suppl):S11–S26.
9. Armitage GC. Development of a classification system for periodontal diseases and conditions. Ann Periodontol 1999;4:1–6.
S41
EF Corbet et al.
10. Armitage GC. Periodontal diagnosis and classification of periodontal diseases. Periodontol 2000 2004;34:9–21.
11. CatonJ, Greenwell H, Mahanonda R, et al. Consensus report:dental
plaque-induced gingival diseases. Ann Periodontol 1999;4:18–19.
12. Lindhe J, Ranney R, Lamster I, et al. Consensus report: chronic
periodontitis. Ann Periodontol 1999;4:38.
13. Lang N, Bartold PM, Cullinan M, et al. Consensus report:
aggressive periodontitis. Ann Periodontol 1999;4:53.
14. Lang N, Soskolne WA, Greenstein G, et al. Consensus report:
necrotizing periodontal diseases. Ann Periodontol 1999;4.
15. Lang N, Soskolne WA, Greenstein G, et al. Consensus report:
abscesses of the periodontium. Ann Periodontol 1999;4:83.
32. Akesson L, Hakansson J, Rohlin M. Comparison of panoramic
and intraoral radiography and pocket probing for the measurement of the marginal bone level. J Clin Periodontol 1992;19:326–
332.
33. Kim TS, Obst C, Zehaczek S, Geenen C. Detection of bone loss
with different X-ray techniques in periodontal patients. J Periodontol 2008;79:1141–1149.
34. Persson RE, Tzannetou S, Feloutzis AG, Bragger U, Persson GR,
Lang NP. Comparison between panoramic and intra-oral radiographs for the assessment of alveolar bone levels in a periodontal
maintenance population. J Clin Periodontol 2003;30:833–
839.
16. Lang NP, Soskolne WA, Greenstein G, et al. Consensus report:
periodontic-endodontic lesions. Ann Periodontol 1999;4:90.
35. American Academy of Periodontology. Parameter on comprehensive periodontal examination. J Periodontol 2000;71:847–
848.
17. Updegrave WJ. The paralleling extension-cone technique in
intraoral dental radiography. Oral Surg Oral Med Oral Pathol
1951;4:1250–1261.
36. Greenwell H. Committee on Research, Science and Therapy.
Position paper: guidelines for periodontal therapy. J Periodontol
2001;72:1624–1628.
18. Ishikawa I, McGuire MK, Mealey B, et al. Consensus report:
localized tooth-related factors that modify or predispose to plaque-induced gingival diseases and periodontitis. Ann Periodontol
1999;4:97.
37. Position paper: diagnosis of periodontal diseases. J Periodontol
2003;74:1237–1247.
19. Australian Radiation Protection and Nuclear Safety Agency.
Code of Practice for Radiation Protection in Dentistry. Canberra:
Australian Government and ARPANSA, 2005.
38. Grubb JE, Greco PM, English JD, et al. Radiographic and periodontal requirements of the American Board of Orthodontics:
a modification in the case display requirements for adult and
periodontally involved adolescent and preadolescent patients. Am
J Orthod Dentofacial Orthop 2008;134:3–4.
20. Australian Radiation Protection and Nuclear Safety Agency.
Safety Guide for Radiation Protection in Dentistry. Canberra:
Australian Government and ARPANSA, 2005.
39. Kantor ML, Slome BA. Efficacy of panoramic radiography in
dental diagnosis and treatment planning. J Dent Res 1989;68:
810–812.
21. Weems RA, Manson-Hing LR, Jamison HC, Greer DF. Diagnostic yield and selection criteria in complete intraoral radiography. J Am Dent Assoc 1985;110:333–338.
40. Tugnait A, Clerehugh DV, Hirschmann PN. Survey of radiographic practices for periodontal disease in UK and Irish
dental teaching hospitals. Dentomaxillofac Radiol 2000;29:376–
381.
22. Zinman E. Dental and legal considerations in periodontal
therapy. Periodontol 2000 2001;25:114–130.
23. Svenson B, Soderfeldt B, Grondahl HG. Attitudes of Swedish
dentists to the choice of dental X-ray film and collimator for oral
radiology. Dentomaxillofac Radiol 1996;25:157–161.
24. Tugnait A, Clerehugh V, Hirschmann PN. Radiographic equipment and techniques used in general dental practice: a survey of
general dental practitioners in England and Wales. J Dent 2003;
31:197–203.
25. Tugnait A, Hirschmann PN, Clerehugh V. Validation of a
model to evaluate the role of radiographs in the diagnosis and
treatment planning of periodontal diseases. J Dent 2006;34:
509–515.
26. Dundar N, Ilgenli T, Kal BI, Boyacioglu H. The frequency of
periodontal infrabony defects on panoramic radiographs of an
adult population seeking dental care. Community Dent Health
2008;25:226–230.
27. Molander B, Ahlqwist M, Grondahl HG. Panoramic and
restrictive intraoral radiography in comprehensive oral radiographic diagnosis. Eur J Oral Sci 1995;103:191–198.
41. Osborne GE, Hemmings KW. A survey of disease changes
observed on dental panoramic tomographs taken of patients
attending a periodontology clinic. Br Dent J 1992;173:166–
168.
42. Boeddinghaus R, Whyte A. Dental panoramic tomography: an
approach for the general radiologist. Australas Radiol
2006;50:526–533.
43. Pepelassi EA, Diamanti-Kipioti A. Selection of the most accurate
method of conventional radiography for the assessment of periodontal osseous destruction. J Clin Periodontol 1997;24:557–
567.
44. Pepelassi EA, Tsiklakis K, Diamanti-Kipioti A. Radiographic
detection and assessment of the periodontal endosseous defects.
J Clin Periodontol 2000;27:224–230.
45. Cosyn J, De Bruyn H. Interclinician disparity in periodontal
decision making: need for consensus statements on surgical
treatment. J Periodontal Res 2007;42:311–317.
46. Needleman IG, Worthington HV, Giedrys-Leeper E, Tucker RJ.
Guided tissue regeneration for periodontal infra-bony defects.
Cochrane Database Syst Rev 2006:CD001724.
28. Jenkins WM, Brocklebank LM, Winning SM, Wylupek M,
Donaldson A, Strang RM. A comparison of two radiographic
assessment protocols for patients with periodontal disease.
Br Dent J 2005;198:565–569; discussion 557; quiz 586.
47. Klein F, Kim TS, Hassfeld S, et al. Radiographic defect depth and
width for prognosis and description of periodontal healing of
infrabony defects. J Periodontol 2001;72:1639–1646.
29. Rohlin M, Kullendorff B, Ahlqwist M, Henrikson CO, Hollender
L, Stenstrom B. Comparison between panoramic and periapical
radiography in the diagnosis of periapical bone lesions. Dentomaxillofac Radiol 1989;18:151–155.
48. Eickholz P, Horr T, Klein F, Hassfeld S, Kim TS. Radiographic
parameters for prognosis of periodontal healing of infrabony
defects: two different definitions of defect depth. J Periodontol
2004;75:399–407.
30. Akesson L, Rohlin M, Hakansson J, Hakansson H, Nasstrom K.
Comparison between panoramic and posterior bitewing radiography in the diagnosis of periodontal bone loss. J Dent
1989;17:266–271.
49. Esposito M, Grusovin MG, Coulthard P, Worthington HV.
Enamel matrix derivative (Emdogain) for periodontal tissue
regeneration in intrabony defects. Cochrane Database Syst Rev
2005:CD003875.
31. Akesson L, Rohlin M, Hakansson J. Marginal bone in periodontal disease: an evaluation of image quality in panoramic and
intra-oral radiography. Dentomaxillofac Radiol 1989;18:105–
112.
50. Sculean A, Schwarz F, Chiantella GC, Arweiler NB, Becker J.
Nine-year results following treatment of intrabony periodontal
defects with an enamel matrix derivative: report of 26 cases. Int J
Periodontics Restorative Dent 2007;27:221–229.
S42
ª 2009 Australian Dental Association
Radiographs for diagnosis and management
51. Pontoriero R, Wennstrom J, Lindhe J. The use of barrier membranes and enamel matrix proteins in the treatment of angular
bone defects. A prospective controlled clinical study. J Clin
Periodontol 1999;26:833–840.
52. Heden G, Wennstrom J, Lindhe J. Periodontal tissue alterations
following Emdogain treatment of periodontal sites with angular
bone defects. A series of case reports. J Clin Periodontol
1999;26:855–860.
53. Sculean A, Windisch P, Keglevich T, Gera I. Histologic evaluation
of human intrabony defects following non-surgical periodontal
therapy with and without application of an enamel matrix protein derivative. J Periodontol 2003;74:153–160.
54. Gutierrez MA, Mellonig JT, Cochran DL. Evaluation of enamel
matrix derivative as an adjunct to non-surgical periodontal
therapy. J Clin Periodontol 2003;30:739–745.
55. Giannopoulou C, Andersen E, Brochut P, Plagnat D, Mombelli A.
Enamel matrix derivative and systemic antibiotics as adjuncts to
non-surgical periodontal treatment: biologic response. J Periodontol 2006;77:707–713.
56. Ramesh A, Tyndall DA, Ludlow JB. Evaluation of a new digital
panoramic system: a comparison with film. Dentomaxillofac
Radiol 2001;30:98–100.
57. Ridao-Sacie C, Segura-Egea JJ, Fernandez-Palacin A, BullonFernandez P, Rios-Santos JV. Radiological assessment of periapical status using the periapical index: comparison of periapical
radiography and digital panoramic radiography. Int Endod J
2007;40:433–440.
58. Pecoraro M, Azadivatan-le N, Janal M, Khocht A. Comparison of
observer reliability in assessing alveolar bone height on direct
digital and conventional radiographs. Dentomaxillofac Radiol
2005;34:279–284.
59. Teeuw WJ, Coelho L, Silva A, et al. Validation of a dental image
analyzer tool to measure alveolar bone loss in periodontitis
patients. J Periodontal Res 2009;44:94–102.
60. Li G, Engstrom PE, Nasstrom K, Lu ZY, Sanderink G, Welander U.
Marginal bone levels measured in film and digital radiographs
corrected for attenuation and visual response: an in vivo study.
Dentomaxillofac Radiol 2007;36:7–11.
radiography. A methodological study. J Clin Periodontol 1988;
15:27–37.
67. Woo BM, Zee KY, Chan FH, Corbet EF. In vitro calibration and
validation of a digital subtraction radiography system using
scanned images. J Clin Periodontol 2003;30:114–118.
68. Lai SM, Zee KY, Lai MK, Corbet EF. Clinical and radiographic
investigation of the adjunctive effects of a low-power He-Ne laser
in the treatment of moderate to advanced periodontal disease:
a pilot study. Photomed Laser Surg 2009;27:287–293.
69. Cury PR, Araujo NS, Bowie J, Sallum EA, Jeffcoat MK. Comparison between subtraction radiography and conventional
radiographic interpretation during long-term evaluation of periodontal therapy in Class II furcation defects. J Periodontol
2004;75:1145–1149.
70. Hwang YJ, Fien MJ, Lee SS, et al. Effect of scaling and root
planing on alveolar bone as measured by subtraction radiography. J Periodontol 2008;79:1663–1669.
71. Naito T, Hosokawa R, Yokota M. Three-dimensional alveolar
bone morphology analysis using computed tomography. J Periodontol 1998;69:584–589.
72. Pistorius A, Patrosio C, Willershausen B, Mildenberger P, Rippen
G. Periodontal probing in comparison to diagnosis by CT-scan.
Int Dent J 2001;51:339–347.
73. Mengel R, Candir M, Shiratori K, Flores-de-Jacoby L. Digital
volume tomography in the diagnosis of periodontal defects: an in
vitro study on native pig and human mandibles. J Periodontol
2005;76:665–673.
74. Misch KA, Yi ES, Sarment DP. Accuracy of cone beam computed
tomography for periodontal defect measurements. J Periodontol
2006;77:1261–1266.
75. Mol A, Balasundaram A. In vitro cone beam computed tomography imaging of periodontal bone. Dentomaxillofac Radiol
2008;37:319–324.
76. Vandenberghe B, Jacobs R, Yang J. Detection of periodontal bone
loss using digital intraoral and cone beam computed tomography
images: an in vitro assessment of bony and ⁄ or infrabony defects.
Dentomaxillofac Radiol 2008;37:252–260.
61. Li G, Engstrom PE, Welander U. Measurement accuracy of
marginal bone level in digital radiographs with and without color
coding. Acta Odontol Scand 2007;65:254–258.
77. Noujeim M, Prihoda T, Langlais R, Nummikoski P. Evaluation
of high-resolution cone beam computed tomography in the
detection of simulated interradicular bone lesions. Dentomaxillofac Radiol 2009;38:156–162.
62. Henriksson CH, Stermer EM, Aass AM, Sandvik L, Moystad A.
Comparison of the reproducibility of storage phosphor and film
bitewings for assessment of alveolar bone loss. Acta Odontol
Scand 2008;66:380–384.
78. Walter C, Kaner D, Berndt DC, Weiger R, Zitzmann NU.
Three-dimensional imaging as a pre-operative tool in decision
making for furcation surgery. J Clin Periodontol 2009;36:250–
257.
63. Lanning SK, Best AM, Temple HJ, Richards PS, Carey A,
McCauley LK. Accuracy and consistency of radiographic interpretation among clinical instructors in conjunction with a training program. J Dent Educ 2006;70:545–557.
64. Gomes-Filho IS, Sarmento VA, de Castro MS, et al. Radiographic
features of periodontal bone defects: evaluation of digitized
images. Dentomaxillofac Radiol 2007;36:256–262.
65. Allen KM, Hausmann E. Analytical methodology in quantitative
digital subtraction radiography: analyses of the aluminum reference wedge. J Periodontol 1996;67:1317–1321.
66. Bragger U, Pasquali L, Rylander H, Carnes D, Kornman KS.
Computer-assisted densitometric image analysis in periodontal
ª 2009 Australian Dental Association
Address for correspondence:
Professor Esmonde Corbet
Periodontology
Prince Philip Dental Hospital
34 Hospital Road
Hong Kong
Email: efcorbet@hkusua.hku.hk
S43