JJOD-2198; No. of Pages 9
Review
Diagnostic accuracy of CBCT for tooth fractures:A meta-analysis
Hu Long, Yang Zhou, Niansong Ye, Lina Liao, Fan Jian,Yan Wang, Wenli Lai *
Department of Orthodontics, State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan
University, Chengdu 610041, Sichuan, China
2
j o u r n a l o f d e n t i s t r y x x x ( 2 0 1 3 ) x x x – x x x
a r t i c l e i n f o
Article history:
Received 17 July 2013
Received in revised form
26 November 2013
Accepted 30 November 2013
Available online xxx
Keywords:
Cone-beam computed tomography
Diagnostic accuracy
Meta-analysis
Root fracture
Systematic review
Tooth fracture
a b s t r a c t
Objectives: The objective of this meta-analysis was to determine the diagnostic accuracy of
cone-beam computed tomography (CBCT) for tooth fractures in vivo.
Methods: PubMed, Embase, Web of Science, ProQuest Dissertations & Theses, CNKI and
SIGLE were searched from January 1990 to April 2013 for eligible studies. Quality Assessment
of Diagnostic Accuracy Studies-2 (QUADAS-2) was employed to assess the quality of the
included studies. Meta-analyses were performed in MetaDisc 1.4, Stata 12.1 and StatsDirect
2.7.9.
Results: Finally, 12 studies were included in this meta-analysis. The pooled sensitivity,
specificity, positive likelihood ratio, negative likelihood ratio and summary receiver oper-
ating characteristic were 0.92 (95% CI = 0.89–0.94), 0.85 (95% CI = 0.75–0.92), 5.68 (95%
CI = 3.42–9.45), 0.13 (95% CI = 0.09–0.18) and 0.94 (95% CI = 0.90–0.98), respectively. The
pooled prevalence of tooth fractures in patients with clinically-suspected but periapical-
radiography-undetected tooth fractures was 91% (95% CI = 83%-97%). Positive and negative
predictive values were 0.98 and 0.43 (subgroup analysis: 0.98 and 0.28 for endodontically-
treated teeth; 0.99 and 0.77 for non-endodontically-treated teeth).
Conclusion: We suggest that CBCT has a high diagnostic accuracy for tooth fractures and
could be used in clinical settings. We can be very confident with positive test results but
should be very cautious with negative test results, especially for endodontically treated
teeth.
# 2013 Elsevier Ltd. All rights reserved.
Available online at www.sciencedirect.com
ScienceDirect
journal homepage: www.intl.elsevierhealth.com/journals/jden
1. Introduction
With the evolution and adaptation of animal species to diet,
their teeth have evolved sophisticated microstructures to
absorb considerably high occlusal forces and to protect their
teeth from fractures,1 although their dental enamel is per se
* Corresponding author at: Department of Orthodontics, State Key LaSichuan University, No. 14, Section 3, Ren Min South Road, Chengdu
E-mail address: [email protected] (W. Lai).
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0300-5712/$ – see front matter # 2013 Elsevier Ltd. All rights reservedhttp://dx.doi.org/10.1016/j.jdent.2013.11.024
highly brittle. Despite these sophisticated microstructures,
tooth fractures are still frequently encountered in dental
practice.3 It has been well documented that the most common
cause of tooth fractures in adults is high occlusal forces caused
by biting on hard objects or abnormal contacts of opposing
teeth.4 In addition, earlier endodontic therapy and malocclu-
sions are implicated in the aetiology of tooth fractures.2,3,5 The
boratory of Oral Diseases, West China Hospital of Stomatology,610041, China. Tel.: +86 2885501442.
BCT for tooth fractures: A meta-analysis. Journal of Dentistry (2013),
.
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JJOD-2198; No. of Pages 9
treatment of tooth fractures often requires an interdisciplin-
ary approach, e.g., combined endodontic–orthodontic–
prosthodontic treatments.6 Thus, tooth fracture is an issue
discussed in almost all the dental specialties.
Unfortunately, the diagnosis of tooth fractures, especial-
ly root fractures, is sometimes difficult for dental practi-
tioners due to their extremely variable clinical presentations
and no pathognomonic signs.7 The most common diagnos-
tic modality for tooth fractures—periapical radiography—
has been revealed to have a low diagnostic accuracy and to
leave many tooth fractures undetected.8–10 The introduction
of cone-beam computed tomography (CBCT) in dentistry
has allowed dental practitioners to acquire three-dimen-
sional visualization of teeth with high spatial resolution and
low radiation.11 Several studies have revealed the outstand-
ing diagnostic accuracy of CBCT for tooth fractures,12–15
especially for those undetected through periapical radiog-
raphy.16 However, these studies based on in vitro tooth
fractures and the diagnostic performance of CBCT for tooth
fractures in vivo has been poorly understood.9,10 Moreover, it
has been reported that not all dental practitioners or dental
students were aware of CBCT.17,18 Therefore, in order to
help practitioners make correct diagnosis and subsequent
prudent treatment decisions, we conducted this meta-
analysis to critically appraise the currently available evi-
dence and to determine the diagnostic accuracy of CBCT for
tooth fractures in vivo.
2. Methods
2.1. Inclusion criteria for included studies
Studies should be those which examined the diagnostic
accuracy of CBCT for tooth fractures in vivo. In vitro studies
and case reports would be excluded. Participants in each study
should be clinically suspected with tooth fractures and
received CBCT examinations for the diagnosis of tooth
fractures. The number of participants in each study should
be at least 10. Furthermore, studies should have reference
tests—surgical exploration or extractions—to establish the
diagnosis of tooth fractures.
Table 1 – Search strategies for each database.
Database
PubMed (Cone-Beam Computed Tomography [Mes
OR CBCT) AND (Tooth Fractures [Mesh] O
Embase (Cone-Beam Computed Tomography OR c
CBCT) AND (tooth fracture OR tooth fract
fractures)
Web of Science (Cone-Beam Computed Tomography OR c
CBCT) AND (tooth fracture OR tooth fract
fractures)
ProQuest Dissertation &
Theses
(cone-beam computed tomography OR con
fracture)
CNKIa (cone beam CT OR CBCT) AND (tooth frac
SIGLE CBCT AND tooth fracture
a Chinese terms were used in CNKI, its search strategy listed above wer
April 2013.
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2.2. Search methods
We searched the electronic databases of PubMed, Embase,
Web of Science, ProQuest Dissertations & Theses and CNKI.
Moreover, the grey literature database of SIGLE was searched.
The specific search strategy for each database is presented in
Table 1. The electronic searching was from January 1990 to
April 2013 with no language restriction. Two review authors
(HL and YZ) conducted the electronic searching independently
and in duplicate. Any disagreement was solved by discussion
or referred to a third author.
2.3. Data extraction and analysis
2.3.1. Data extraction
Demographic data, reference test, true positive, false positive,
false negative and true negative were extracted and recorded
independently and in duplicate by two reviewer authors (HL
and YZ).
2.3.2. Study outcomesStudy outcomes were sensitivity, specificity, positive likeli-
hood ratio (LR), negative LR and summary receiver operating
characteristic (SROC). Moreover, derivative outcomes (preva-
lence, positive predictive value (PPV) and negative predictive
value (NPV)) were calculated from the study outcomes
mentioned above.
2.3.3. Quality assessmentThe quality of each included study was evaluated according to
Quality Assessment of Studies of Diagnostic Accuracy-2
(QUADAS-2).19 Specifically, for each category (risk of bias
and applicability concerns), studies with two or more domains
of high risk would be designated as high risk; those with only
one domain of high risk would be designated as medium risk;
those with no domain of high risk would be designated as low
risk. Assessments were conducted independently and in
duplicate by two review authors.
2.3.4. Data analysisOutcome data, i.e., sensitivity, specificity, positive LR, negative
LR and SROC, would be statistically pooled. Moreover,
Search strategy
h] OR cone-beam CT OR cone beam CT OR cone-beam OR cone beam
R tooth fracture* OR dental fracture* OR root fracture*)
one-beam CT OR cone beam CT OR cone-beam OR cone beam OR
ures OR dental fracture OR dental fractures OR root fracture OR root
one-beam CT OR cone beam CT OR cone-beam OR cone beam OR
ures OR dental fracture OR dental fractures OR root fracture OR root
e beam CT OR CBCT) AND (tooth fracture OR dental fracture OR root
ture OR root fracture OR fracture)
e English translations. Limits: publication date from January 1980 to
BCT for tooth fractures: A meta-analysis. Journal of Dentistry (2013),
Fig. 1 – PRISMA flow diagram for studies retrieved through
the searching and selection processes.
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prevalences of tooth fractures, non-fractures, positive test
results and negative test results were statistically pooled
through Freeman–Tukey arcsine square root transformation
for variance stabilization.20,21 PPV and NPV were calculated
through Bayes’ theorem.22 Heterogeneity across studies was
assessed through I2 statistic. An I2 statistic greater than 50%
was considered substantial heterogeneity. If substantial
heterogeneity existed, subgroup analysis or meta-regression
would be conducted to explore the heterogeneity. Mantel–
Haenszel fixed effect model would be used when a common
effect size is shared among includes studies; otherwise,
DerSimonian–Laird random effect model would be used.23
In addition, even if a common effect size is shared among all
studies, a random effect model would be adopted when
significant heterogeneity existed (I2 > 50%).23
Sensitivity analysis was performed to assess the robust-
ness of the pooled results in the meta-analyses. Moreover,
publication bias was evaluated based on a regression test and
funnel plot designed specifically for diagnostic systematic
reviews.24 All the statistical analyses were performed in Meta-
Disc 1.4,25 Stata 12.1 (StataCorp, College Station, TX, USA) and
StatsDirect 2.7.9 (StatsDirect Ltd., Cheshire, UK).
3. Results
3.1. Description of included studies
Initially, we identified 154 articles from the database and
excluded 137 irrelevant articles. The remaining 17 articles
were further assessed for eligibility and 128–10,26–34 were finally
included in this meta-analysis. Specifically, the detailed
procedures of electronic searching are shown in Fig. 1. Among
Table 2 – Characteristics of included studies.
Study Samplesize (teeth)
Age(yrs)
Fracturetype
Tooth statu
Du (2010) 40 36.6 Vertical Non-endodont
Liu (2010) 40 57 Vertical and
oblique
–
Edlund (2011) 32 20–70 Vertical Endodontic
Ning (2011) 17 63 Vertical Both
Qin (2011) 47 26–58 – –
Wang (2011) 135 22–82 Vertical and
oblique
Both
Xue (2011) 84 20–89 Vertical Both
Yan (2011) 23 – Vertical Both
Ding (2012) 38 57 Alla Both
Kajan (2012) 10 21–70 All Endodontic
Metska (2012) 39 – Vertical Endodontic
Liu (2013) 31 45 – –
a All is indicative of vertical, oblique and horizontal fractures.
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the included studies, sample sizes ranged from 10 to 135 teeth.
Fracture types included vertical, oblique and horizontal tooth
fractures. Both non-endodontically and endodontically trea-
ted teeth were included. All studies verified tooth fractures
through reference standards, i.e., surgical extraction or
exploration. The detailed characteristics of each study are
presented in Table 2.
3.2. Quality assessment
According to QUADAS-2, the quality assessment comprised two
categories: risk of bias and applicability concerns. In this meta-
analysis, although risk of bias of included studies was medium
to high, the applicability was of medium to low risk (Table 3).
s CBCT Reference test
ic NewTom 3 G; 110 kV, 6 mA, 9 s Surgical extraction
or exploration
Planmeca ProMax 3D Surgical extraction
or exploration
iCAT or 3D Accuitomo 80;
voxel: 80 or 125 mm
Surgical exploration
3DX multi-image micro-CT; 80 kV,
5 mA, 20 s; voxel: 125 mm
Surgical extraction
or exploration
Kodak 9000C 3D Surgical extraction
or exploration
3DX Accuitomo; 80 kV, 5 mA,
17.5 s; voxel: 125 mm
Surgical extraction
or exploration
Galileos Comfort; 85 kV,
35 mA s; voxel: 125 mm
Surgical extraction
or exploration
3DX multi-image micro-CT;
80 kV, 5 mA, 17.5 s
Surgical extraction
KaVo 3D eXam; 90–120 kV,
3–7 mA; voxel 125 mm
Surgical extraction
or exploration
NewTom VG; 110 kV, 5.5 mA, 5.4 s Surgical extraction
NewTom 3 G or 3D Accuitomo 170;
110 kV, 3.9–5.6 mA or 90 kV, 5 mA;
voxel: 200 or 80 mm
Orthograde retreatment,
surgical exploration
or extraction
Planmeca ProMax 3D Surgical extraction
BCT for tooth fractures: A meta-analysis. Journal of Dentistry (2013),
Table 3 – Quality assessment of the included studies according to QUADAS-2.
Study Risk of bias Applicability concerns
Patientselection
Indextest
Reference Flow &timing
Total Patientselection
Indextest
Reference Total
Du (2010) High Low High High High Low Low High Medium
Liu (2010) High Unclear Low Low Medium Low Unclear Low Low
Edlund (2011) High High Low Low High Low High Low Medium
Ning (2011) High Low Low Low Medium Low Low Low Low
Qin (2011) High Low High High High Low Low High Medium
Wang (2011) High Low Low Low Medium Low Low Low Low
Xue (2011) Unclear Low High High High Unclear Low High Medium
Yan (2011) High Unclear High High High Low Unclear High Medium
Ding (2012) High Unclear Low Low Medium High Unclear Low Medium
Kajan (2012) High Unclear Low High High Low Unclear Low Low
Metska (2012) High Low Low High High Low Low Low Low
Liu (2013) Unclear Unclear Low Low Low Unclear Unclear Low Low
High: high risk; unclear: unclear risk; low: low risk.
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3.3. Description of outcomes
All the study outcomes proposed above were evaluated among
the included studies, i.e., sensitivity, specificity, positive LR,
negative LR and SROC.
3.4. Statistical pooling of outcomes
3.4.1. Sensitivity and specificityConsidering that a common effect size was shared among
studies and no significant heterogeneity existed for
Fig. 2 – The pooled diagnostic indices for the diagnosis of tooth
diagnosis of tooth fractures through CBCT; (B) the pooled specif
the pooled positive likelihood for the diagnosis of tooth fracture
the diagnosis of tooth fractures through CBCT.
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sensitivity and specificity (I2 = 38.7% and 24.5%, respective-
ly), the Mantel–Haenszel fixed effect model was employed.
As displayed in Fig. 2 A and B, the results showed
that the pooled sensitivity and specificity were 0.92
(95% CI = 0.89–0.94) and 0.85 (95% CI = 0.75–0.92), respective-
ly.
3.4.2. Positive LR and negative LR
Since a common effect size was shared among studies and no
significant heterogeneity existed (I2 = 26.7% and 0.0%, respec-
tively), fixed effect model was used. The results revealed that
fractures through CBCT. (A) The pooled sensitivity for the
icity for the diagnosis of tooth fractures through CBCT; (C)
s through CBCT; (D), the pooled negative likelihood ratio for
BCT for tooth fractures: A meta-analysis. Journal of Dentistry (2013),
Fig. 3 – Summary receiver operating characteristics (SROC) curve for the diagnosis of tooth fractures through CBCT.
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the pooled positive LR and negative LR were 5.68 (95%
CI = 3.42–9.45) and 0.13 (95% CI = 0.09–0.18), respectively
(Fig. 2C and D).
3.4.3. SROCThe SROC curve for discrimination of fractures and non-
fractures is presented in Fig. 3. The pooled area under curve
(AUC) of SROC was 0.94 (95% CI = 0.90–0.98).
Fig. 4 – The pooled prevalence of tooth fractures in patients
with clinically-suspected but periapical-radiography-
undetected tooth fractures.
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3.5. Prevalences
Although a common effect size was shared among the
included studies, random effect model was employed due to
significant heterogeneity (I2 = 87.6% for tooth fractures and
non-fractures; I2 = 87.2% for positive and negative test results).
The meta-analysis revealed that the pooled prevalence of
tooth fractures was 0.91 (95% CI = 0.83–0.97) (Fig. 4). Moreover,
the results showed that the pooled prevalences of non-
fractures, positive test results and negative test results were
0.09 (95% CI = 0.03–0.17), 0.87 (95% CI = 0.78–0.94) and 0.13 (95%
CI = 0.06–0.22), respectively.
3.6. PPV and NPV
Through Bayes’ theorem,22 PPV and NPV were calculated to be
0.98 and 0.43. Moreover, PPV and NPV were 0.99 and 0.77 for
non-endodontically treated teeth; PPV and NPV were 0.98 and
0.28 for endodontically treated teeth.
3.7. Sensitivity analysis
Since reference standard test was not applied in all the
patients in three studies,26,29,32 a sensitivity analysis was
performed by excluding these three studies, but no significant
changes were found (Table 4).
Seven included studies exhibited high risk of bias (Table 3),
thus we performed a sensitivity analysis by excluding these
studies with high risk of bias and found a moderate but non-
significant increase in diagnostic accuracy (Table 4).
Changes in effect models (fixed vs. random effect model)
failed to reveal any significant change in the pooled results
(Table 4).
BCT for tooth fractures: A meta-analysis. Journal of Dentistry (2013),
Table 4 – Sensitivity analysis and subgroup analysis.
Item Sensitivity Specificity Positive LR Negative LR SROC PPV NPV
Original estimate 0.92 (0.89, 0.94) 0.85 (0.75, 0.92) 5.68 (3.42, 9.45) 0.13 (0.09, 0.18) 0.94 (0.90, 0.98) 0.98 0.43
Random effect model 0.92 (0.89, 0.94) 0.85 (0.75, 0.92) 3.49 (1.91, 6.40) 0.13 (0.09, 0.18) 0.94 (0.90, 0.98) 0.97 0.43
Gold standard reference test 0.91 (0.88, 0.94) 0.85 (0.75, 0.92) 5.76 (3.35, 9.91) 0.13 (0.09, 0.20) 0.94 (0.89, 0.99) 0.98 0.43
Exclusion of high risk of bias 0.94 (0.90, 0.97) 0.93 (0.81, 0.99) 10.98 (4.12, 29.29) 0.10 (0.06, 0.18) 0.98 (0.95, 1.00) 0.99 0.50
Inclusion of only low risk of
applicability
0.92 (0.88, 0.95) 0.86 (0.75, 0.94) 6.35 (3.35, 12.05) 0.13 (0.08, 0.21) 0.95 (0.89, 1.00) 0.98 0.43
Subgroup analysis on
vertical fracture
0.89 (0.84, 0.93) 0.73 (0.55, 0.87) 3.40 (1.87, 6.17) 0.18 (0.10, 0.29) 0.88 (0.77, 0.99) 0.97 0.35
Subgroup analysis on
endodontic teeth
0.82 (0.72, 0.89) 0.82 (0.68, 0.92) 4.19 (2.82, 7.69) 0.25 (0.16, 0.39) 0.90 (0.81, 0.98) 0.98 0.28
Subgroup analysis on
non-endodontic teeth
0.97 (0.92, 0.99) 0.95 (0.76, 1.00) 13.70 (3.01, 62.42) 0.03 (0.01, 0.11) – 0.99 0.77
PPV: positive predictive value; NPV: negative predictive value.
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Among the included studies, fracture types consisted of
vertical, oblique and horizontal (Table 2). However, the
differential diagnostic accuracy of CBCT can only be assessed
for vertical fracture. Thus, we conducted a subgroup analysis
on vertical tooth fracture and found that a moderate but non-
significant decrease in diagnostic accuracy (Table 4).
Both endodontically and non-endodontically treated teeth
were studied in the included studies. Among the included
studies, only Wang 201130 evaluated the differential diagnostic
accuracy of CBCT for each type. In total, two and four studies
assessed the differential diagnostic accuracy of CBCT for non-
endodontically and endodontically treated teeth, respectively.
Thus, we performed a subgroup analysis and found that the
sensitivity of CBCT was significantly higher for non-endodon-
tically treated teeth (sensitivity: 0.97, 95% CI = 0.92–0.99) than
for endodontically treated teeth (sensitivity: 0.82, 95% CI = 0.72–
0.89). Moreover, a moderate but non-significant increased
diagnostic accuracy was found for non-endodontically treated
teeth regarding specificity, positive LR and negative LR (Table 4).
3.8. Cumulative meta-analysis
Cumulative met-analysis was performed to determine the
chronological changes in diagnostic accuracy of CBCT for
tooth fractures. The results showed no significant changes
over time (data not shown).
3.9. Assessment of publication bias
Since Egger’s regression test and Begg’s rank correlation test
would inflate Type I error and are unsuitable for diagnostic
systematic review, we employed an adapted Egger’s and
Begg’s tests specifically for diagnostic systematic reviews.24
The results revealed that neither adapted Egger’s (p = 0.12) nor
Begg’s test (p = 0.84) indicated any evidence of publication
bias.
4. Discussion
In this meta-analysis, the included 12 studies evaluated five
outcomes. The pooled sensitivity, specificity, positive LR,
negative LR and SROC were 0.92, 0.85, 5.68, 0.13 and 0.94,
respectively. Sensitivity analysis and subgroup analysis
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showed consistent results in the meta-analysis except for
the subgroup analysis on non-endodontically and endodonti-
cally treated teeth. Cumulative meta-analysis revealed no
significant changes over time regarding the diagnostic
accuracy of CBCT for tooth fractures. Furthermore, neither
modified Egger’s test nor Begg’s test was indicative of any
evidence of publication bias. Thus, in general, the results in
the meta-analysis were robust.
According to QUADAS-2,19 qualities of included studies for
diagnostic systematic review comprised two categories: risk of
bias and applicability concerns. Specifically, risk of bias
evaluates the potential for bias in each included studies while
applicability concerns assess the potential for generalization
or applicability of the results to real clinical scenarios. The
results showed that risk of bias was medium to high and the
applicability was of medium to low risk. In almost all the
included studies, prior to CBCT exams, subjects were firstly
diagnosed through periapical radiography but no convincing
diagnosis was established. With regards to risk of bias, these
included studies suffered from a significant bias—inappropri-
ate patient selection. Specifically, these periapical-radiogra-
phy-undetected patients were ‘‘difficult-to-diagnose’’ patients
and may result in an underestimation of diagnostic accuracy
of CBCT in this meta-analysis. Thus, high risk of bias was
assigned to the category—risk of bias. Despite high risk of bias,
the sensitivity analysis on exclusion of high risk of bias
resulted in no significant changes in the results (Table 4),
indicative of robustness of the results from the meta-analysis.
Moreover, this is closer to real clinical scenarios: patients with
clinically-suspected tooth fractures would be first diagnosed
through periapical radiographs and, if undetected, would be
further diagnosed by using CBCT. Thus, low risk was assigned
to the category—applicability concerns. Similarly, a sensitivity
analysis on inclusion of studies with low risk of applicability
failed to reveal any significant change (Table 4). Since CBCT for
tooth fracture is a clinical application rather than a theoretical
issue, we would focus on its applicability and suggest that
quality of the included studies in this meta-analysis are
medium to high (medium to low risk).
In this meta-analysis, all included studies employed
surgical extraction or exploration to establish the reference
standard results. However, among the included studies,
three26,29,32 did not apply the reference standard tests in all
the patients, which may bias the results in the meta-analysis.
BCT for tooth fractures: A meta-analysis. Journal of Dentistry (2013),
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We performed a sensitivity analysis by excluding the three
studies and found no significant changes from the original
estimates, which indicates that the results in the meta-
analysis were robust and not biased by these three studies.
The results revealed that pooled sensitivity and specificity
were 0.92 and 0.85, respectively. By definition, sensitivity is the
proportion of those with disease who have positive test results
while specificity is the proportion of those without diseases who
have negative test results. Thus, the results indicated that,
among a group of patients with both tooth fractures and no
fractures, 92% of the tooth fractures could be detected and 85%
of the non-fractures could be ruled out through CBCT. Or
alternatively, for a patient with tooth fractures, the chance of
the diagnosis of tooth fracture is 92%; for a healthy person
without tooth fracture, the chance of the diagnosis of non-
fracture is 85%.
However, there would always be a trade-off between
sensitivity and specificity.35 Thus, the two indices cannot
reflect the diagnostic accuracy well individually. For this
purpose, SROC has been proposed as an index to assess the
diagnostic accuracy in meta-analyses36–38 and has been used in
many recent diagnostic meta-analyses.35,39 SROC curve was
constructed by plotting sensitivity against 1-specificity, thereby
integrating both sensitivity and specificity into one index. In
practice, the area under curve (AUC) of SROC has a range from
0.5 (no better than chance) to 1 (perfect test).38 In our study, the
meta-analysis revealed that the pooled AUC of SROC was 0.94
(95% CI = 0.90–0.98), which indicates that CBCT has a high
diagnostic accuracy for the diagnosis of tooth fractures.
The meta-analysis showed that the pooled positive LR and
negative LR were 5.68 and 0.13, respectively. By definition,
positive LR is the ratio of the true positive rate to the false
positive rate and negative LR is the ratio of the false negative
rate to the true negative rate. Thus, a diagnosis would be more
accurate when positive LR becomes higher and negative LR
becomes lower. It has been documented that positive LR
greater than 5 or negative LR less than 0.2 can provide strong
diagnostic evidence.40 Therefore, our results (positive
LR = 5.68 > 5; negative LR = 0.13 < 0.2) indicate that CBCT is
able to give a strong diagnostic value regarding tooth fractures.
Given the prevalence of tooth fractures, through Bayes’
theorem,22 we are able to calculate the probabilities of true
fracture and non-fracture among positive and negative test
results, defined as positive and negative predictive values,
respectively. The specific patient population in this meta-
analysis is those with clinically suspected tooth fractures but
undetected through periapical radiographs. The meta-analy-
sis showed that the pooled prevalence of tooth fracture in this
specific patient population was 0.91 (95% CI = 0.83–0.97). Then,
the positive and negative predictive values were calculated to
be 0.98 and 0.43. This indicates that, for a given patient
diagnosed with tooth fractures by CBCT in this specific patient
population, we have 98% confidence to say that he really has
tooth fracture. Moreover, for a given patient diagnosed with
non-fractures by CBCT, we have only 43% confidence to say
that he is really free from tooth fractures, even worse than
chance. However, these positive and negative predictive
values would be susceptible to changes for different patient
populations with different prevalences of tooth fractures41:
the positive and negative predictive values would be 0.85 and
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0.88 if the prevalence of tooth fracture is 50%. Thus, the
positive and negative predictive values calculated in this
meta-analysis could be used in only the aforementioned
specific patient population—those with clinically suspected
tooth fractures but undetected by periapical radiographs. In
real clinical scenarios, if a patient (clinically suspected tooth
fractures but undetected by periapical radiographs) is diag-
nosed with tooth fractures through CBCT, we can be very
confident that he suffered from tooth fractures and refer him
to have his fractured teeth treated. If a patient is diagnosed
without tooth fractures through CBCT (chances of negatives
are very low in the real clinical scenarios since the pooled
prevalence of negative test result is 13% for this subgroup of
patients), we have only 43% of confidence of non-fractures and
we suggest that a close follow-up is needed.
Tooth fractures can be divided into different types based on
the directions of fractures: vertical, horizontal, oblique. For
different types of tooth fractures, diagnoses may be different.
Unfortunately, in this meta-analysis, due to unavailability of
original data, we were able to perform a subgroup analysis
only for vertical tooth fractures, but failed to find any
significant change from the original estimates (Table 4). This
finding suggests the diagnostic accuracy of CBCT is similar
among different types of tooth fractures.
It has been reported that the diagnostic accuracy of CBCT
for endodontically-treated teeth can be reduced,42,43 which
can be attributed to potential artefacts caused by root canal
fillings. Consistently, in this meta-analysis, we found that
sensitivity was significantly higher in non-endodontically
treated teeth than in endodontically treated teeth [0.97 (95%
CI = 0.92–0.99) vs. 0.82 (95% CI = 0.72–0.89)] while other indices
(specificity, positive LR, negative LR and SROC) were similar.
This indicates that, in clinical scenarios, the chance of
diagnosis of tooth fractures is 97% for a non-endodontically
treated tooth with fractures and that chance would be 82% for
an endodontically treated tooth with fractures. Moreover, let
the prevalence be 91%, the positive predictive values were
calculated to be similar: 0.98 and 0.99 for endodontically and
non-endodontically treated teeth, respectively; while negative
predictive values were 0.28 and 0.77 for endodontically and
non-endodontically treated teeth, respectively. Based on the
CBCT results, we can easily know whether a tooth is an
endodontically or non-endodontically treated tooth. If the
result is positive, regardless of whether it is an endodontically
or non-endodontically treated tooth, it is almost 100% chance
of tooth fractures. However, if the result is negative, chances
of false negatives are much higher for endodontically treated
teeth (100–28% = 72%) than for non-endodontically treated
teeth (100–77% = 23%) and we should be very cautious for
these endodontically treated teeth with negative results.
The limitations of this meta-analysis were small sample
sizes in some studies, no applying reference standard test for
all patients in some studies, and unavailability of data for
subgroup analysis for horizontal and oblique tooth fractures.
Moreover, as mentioned in Table 2, CBCT devices and
exposure protocols differed among included studies. Since
image quality may vary among different CBCT devices and
exposure protocols,44,45 the results in this meta-analysis
should be interpreted with caution and may not be applied
to all CBCT devices.
BCT for tooth fractures: A meta-analysis. Journal of Dentistry (2013),
Fig. 5 – A recommended diagnostic pathway for patients
with clinically suspected tooth fractures.
j o u r n a l o f d e n t i s t r y x x x ( 2 0 1 3 ) x x x – x x x8
JJOD-2198; No. of Pages 9
5. Clinical implications
According to European Guidelines (Radiation Protection 172:
cone beam CT for dental and maxillofacial radiology)46 and the
results in this meta-analysis, we suggest the following diagnos-
tic pathway for patients with clinically-suspected tooth frac-
tures (Fig. 5). A patient with clinically-suspected tooth fractures
should be firstly diagnosed through periapical radiography. If
tooth fractures are detected by periapical radiography, subse-
quent treatments should follow; if tooth fractures are not
detected by the periapical radiography but symptoms persist,
CBCT should be prescribed for further diagnosis. If tooth
fractures are found by CBCT, regardless of endodontically or
non-endodontically treated teeth, treatments should ensue; if
tooth fractures are not found by CBCT, we should be very
cautious due to chances of false negatives and thus close follow-
ups are needed. Particularly, special attention should be given to
endodontically treated teeth with negative CBCT findings.
Furthermore, in this meta-analysis, almost all the included
participants were adults, thus the results should be limited to
adults. Although CBCT exams for tooth fractures enjoy the
aforementioned advantages, due to radiation risks, we suggest
that CBCT exams for tooth fractures should be used unless
good justifications are made (tooth fractures cannot be
detected through periapical radiography). Moreover, radiation
risks of CBCT are higher in children than in adults,46 thus we
should be very cautious for prescribing CBCT exams in
children. For the diagnosis of tooth fractures through CBCT,
small and medium field of view (FOV) (effective dose: 11–
674 mSV) should be used rather than large FOV (effective dose:
30–1073 mSV) for radiation protection.46
6. Conclusion
We suggest that CBCT has a high diagnostic accuracy for tooth
fractures and could be used in clinical settings. We can be very
confident with positive test results but should be very cautious
with negative test results. For patients with negative results,
close follow-ups are recommended.
The diagnostic accuracy of CBCT is similar among different
types of tooth fractures, which should be interpreted with
Please cite this article in press as: Long H, et al. Diagnostic accuracy of Chttp://dx.doi.org/10.1016/j.jdent.2013.11.024
caution due to unavailability of data for subgroup analysis on
horizontal and oblique tooth fractures.
The diagnostic accuracy of CBCT is higher in non-
endodontically treated teeth than in endodontically treated
teeth. We can be very confident with the positive results for
both but should be cautious with the negative results
especially for endodontically treated teeth.
Clinical significance
Through an extensive meta-analysis, this systematic review
critically examines the diagnostic performance of CBCT for
tooth fractures and provides an evidence-based diagnostic
pathway for tooth fractures. This diagnostic pathway would
be beneficial for practitioners to make correct diagnosis and
prudent treatment decisions.
Acknowledgement
This work was supported by National Natural Science
Foundation of China (NSFC), Nos. 81070858 and 81100778.
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