Available online at www.rsu.ac.th/rjas
Rangsit Journal of Arts and Sciences, January-June 2015
Copyright © 2011, Rangsit University
RJAS Vol. X No. X, pp. C-1-C-5
ISSN 2229-063X (Print)/ISSN 2392-554X (Online)
The accuracy of reformatted panoramic radiographic image
in detecting C-shaped canal of mandibular second molar
Prattana Yodmanotham1*, Paitoon Maneeroongrat2, Tanyakan Nithiakarathitikul3, Nattavit Charensuk4,
Tanaporn Tubcharoen5, Wittawin Wongserbchat6, Pranpat Chaiyakul7, Patthamon Koraviyothin8,
Lalita Tangratchatakul9, Tassuda Buranupakorn10, and Sarawut Wechphanich11
1Faculty
of Dentistry, Rangsit University, Patumthani 12000, Thailand
E-mail: prattana.y@rsu.ac.th
2Laboratory engineer, Advanced Dental Technology Center, Pathumthani 12000, Thailand
E-mail: iampaitoon@adtec.or.th
3Undergraduated student, Faculty of Dentistry, Rangsit University, Patumthani12000, Thailand
E-mail: tunyakan_nithi@hotmail.com
4Undergraduated student, Faculty of Dentistry, Rangsit University, Patumthani12000, Thailand
E-mail: zahnarztik@windowslive.com
5Undergraduated student, Faculty of Dentistry, Rangsit University, Patumthani12000, Thailand
E-mail: peed_ss@hotmail.com
6Undergraduated student, Faculty of Dentistry, Rangsit University, Patumthani12000, Thailand
E-mail: withawin01@gmail.com
7Undergraduated student, Faculty of Dentistry, Rangsit University, Patumthani12000, Thailand
E-mail: tapnarp@hotmail.com
8Undergraduated student, Faculty of Dentistry, Rangsit University, Patumthani12000, Thailand
E-mail: sugarbunny_mko@hotmail.com
9
Undergraduated student, Faculty of Dentistry, Rangsit University, Patumthani12000, Thailand
E-mail: minimmod@icloud.com
10Undergraduated student, Faculty of Dentistry, Rangsit University, Patumthani12000, Thailand
E-mail: por_pla_ngo@windowslive.com
11Undergraduated student, Faculty of Dentistry, Rangsit University, Patumthani12000, Thailand
E-mail: sarawut_pat@hotmail.com
*Corresponding authors
Submitted date month, year; accepted in final form date month, year (To be completed by RJAS)
Abstract
The aim of this study was to evaluate the accuracy of reformatted panoramic images in detection
of C-shaped canal on permanent mandibular second molars (PMSMs) compared to axial cone-beam
computed tomographic images (axial-CBCT). 564 CBCT images (1008 PMSMs) of Thai patients were
gathered from two dental institutes and interpreted via CS 3D Imaging Software (Carestream Dental
Atlanta, USA). Reformatted panoramic images and axial CBCT images were inspected by two independent
observers. The C-shaped canal were recorded according to Fan’s classification (2004). The accuracy,
sensitivities, specificities, Positive productive values (PPV) and negative productive values (NPV) of
C-shaped canal finding were calculated. The study shows that a C-shaped canal was identified in 230
(22.82% ) of 1008 PMSMs. The accuracy of reformatted panoramic radiographic images in detection of
C-shaped canal on PMSMs was 84.52% Thus, reformatted panoramic images have high accuracy, good
sensitivities and specificities for detected of C-shaped canal on PMSMs. However, other examination tools
are also added for diagnosis before endodontic treatment.
Keywords: CBCT images, C-shapes canal, reformatted panoramic images, endodontic treatment
Available online at www.rsu.ac.th/rjas
Rangsit Journal of Arts and Sciences, January-June 2015
Copyright © 2011, Rangsit University
RJAS Vol. X No. X, pp. C-1-C-5
ISSN 2229-063X (Print)/ISSN 2392-554X (Online)
1. Introduction
An irregular type of root canal, the “C”
configuration of the canal that has been called
C-shaped canal presents the clinical challenges and
difficulties to diagnose and performs the root canal
therapy. This variation was firstly reported by
Cooke and Cox (1979) which detected the form via
periapical radiographs. Reports in the past showed
that C-shaped canals were found in maxillary
lateral incisor and all maxillary molars. They were
also detected in mandibular central and lateral
incisor, including all the mandibular molars (Kato
et al., 2014). However, this variation is mostly
seen in permanent mandibular second molars
(PMSMs). Manning et al. (1990) reported that the
main anatomical feature of C-shaped root canal
presented as fin and web intercommunicated with
each individual main canal. However, it is
sometimes difficult to diagnose the C-shaped root
canal and impossible to identify their variations
and configurations from conventional radiography.
The gold standard for the study of root
canal morphology was clearing and staining
technique, but it was impossible to perform this
method in vivo. Recently, cone beam computed
tomography (CBCT) image had been found to be
useful and accurate in detecting and accessing root
canal morphology similar to clearing and staining,
according to the studies by Silva et al. and
Demirbuga et al. (2013). However, CBCT was not
taken routinely in dental care system because of
cost-effective reason, unlike panoramic radiograph
which was commonly used for routine dental
examination. Therefore, the aim of this study is to
evaluate the accuracy of reformatted panoramic
images in detecting C-shaped canal of mandibular
second molar compared to the axial dimensional
section images from CBCT.
with complete root formation, (2) age of patients
were informed, (3) adequate quality for
interpretation and the number of root canals. On
the contrary, those CBCT images with at least one
of these exclusion criteria were excluded from the
observation: (1) absences of any PMSMs, (2)
PMSMs with metallic restorative materials
(amalgam filling, metal onlay, or crown) causing
artifacts that superimpose with the root canal, (3)
PMSMs with history of endodontic treatment, and
(4) defective radiographic images. The software
used for CBCT images interpretation was CS 3D
Imaging Software v.3.3.9 (Carestream Dental,
Atlanta, USA). Two observers would interpret
reformatted panoramic images to rule out teeth
with C-shaped canal appearance according to
Fan’s classification (2004) (Fig1). These
reformatted panoramic images were re-constructed
from CBCT data using CS 3D Imaging Software.
Kappa analysis was used for intra-observer, while
percentage of agreement was performed for interobservers calibration. Both tests were executed
immediately after image assessment. When
disagreements occur between two observers during
the analysis, the final judgment would be
determined by a supervising experienced
endodontic specialist. The accuracy, sensitivities,
specificities, Positive productive values (PPV) and
negative productive values (NPV) were calculated
for evaluate the diagnostic value of reformatted
panoramic radiographic images.
2. Objective
To evaluate the accuracy of reformatted
panoramic images in the detection of C-shaped
canal compared to axial images of CBCT.
3. Materials and methods
A total of 1,172 CBCT images were
initially gathered from two dental institutes. One
set of 1,006 images were requested from the
database of Advance Dental Technology Center
(ADTEC), Pathum Thani, Thailand, since 2005 to
2013. Another 166 images were requested from the
database of Faculty of Dental Medicine, Rangsit
University, Pathum Thani, Thailand, since 2008 to
2014. The CBCT images with these following
inclusion criteria were included: (1) containing left
and right permanent mandibular second molars
Figure 1 Fan’s classification (2004)
Figure 1a: mesial and distal halves, the mesial and
distal canals join at the apical portion of
root
Figure 1b: conical root with radiolucent line
separating mesial and distal halves, the
mesial and distal canals did not join only
one mesial strip-liked dentin connection
exists between the peninsula-liked floor
and the mesial wall, which separates the
C-shaped groove into small ML orifice
and one large MB-D orifice
Figure 1c: conical root with radiolucent line
separating mesial and distal halves, one
canal superimposed with the radiolucent
line
Available online at www.rsu.ac.th/rjas
Rangsit Journal of Arts and Sciences, January-June 2015
Copyright © 2011, Rangsit University
Reformatted
Panoramic Images
RJAS Vol. X No. X, pp. C-1-C-5
ISSN 2229-063X (Print)/ISSN 2392-554X (Online)
C
M
Figure 2.1
Figure 2.2
Figure 2.3
Figure 2.4
Figure 2 Representative reformatted panoramic images corresponding to the axial images at
coronal (C) and middle (M) levels.
Figure 2.1: C-shaped canal configuration was interpreted from reformatted panoramic
images and was detected from the axial images.
Figure 2.2: Normal canal configuration was interpreted from reformatted panoramic
images with C-shaped canal configuration detected in axial images.
Figure 2.3: C-shaped canal was interpreted from reformatted panoramic images with
normal canal configuration detected from axial images.
Figure 2.4: Normal canal configuration was interpreted from reformatted panoramic
images and was detected from the axial images.
Available online at www.rsu.ac.th/rjas
Rangsit Journal of Arts and Sciences, January-June 2015
Copyright © 2011, Rangsit University
RJAS Vol. X No. X, pp. C-1-C-5
ISSN 2229-063X (Print)/ISSN 2392-554X (Online)
Table 1 Comparison between axial and reformatted panoramic observation in C-shaped canal detection of PMSMs.
Detection in Axial Images
Interpretation in
Reformatted Panoramic
Images
C-Shaped
Normal*
CShaped
181 (17.96%)
107 (10.62%)
288 (28.57%)
Normal*
49 (4.86%)
671 (66.57%)
720 (71.43%)
230 (22.82%)
778 (77.18%)
1008 (100.00%)
Total
*Teeth
with root canal system not belonging to C-shape.
4. Results
The C-shaped canal was identified in
230(22.82% ) of 1008 PMSMs. There were 17.69%
C-shaped canal configurations detected in both
reformatted panoramic คุ ว ย and the axial CBCT
images. 4.86% of C-shaped canal was only
detected in axial images and 10.62% of C-shaped
canal was only detected in reformatted panoramic
images. Furthermore, 66.57% were not found in
both reformatted panoramic and the axial images.
The results from validity test of
reformatted panoramic interpretation in this study
were calculated and showed 84.52% accuracy,
0.62 positive predictive value (PPV), 0.93 negative
predictive value (NPV), 0.79 sensitivity, and 0.86
specificity.
The results from validity test of
reformatted panoramic interpretation in this study
were calculated and showed 84.52% accuracy,
62.85% positive predictive value (PPV), 93.19%
negative predictive value (NPV), 78.70%
sensitivity, and 86.25% specificity.
5. Discussion
According to the results obtained from
this study, the prevalence of C-shaped canal in
PMSMs in this study was 22.82%. Nonetheless,
the past study in Thai population by Gulabivala
et al. (2002) demonstrated different results. They
studied the root and canal morphology of
mandibular molars in Thai population using
clearing and staining technique. The prevalence of
C-shaped canal according to their study was 10%.
However, CBCT technique was not used for the
evaluation of C-shaped canal in PMSMs in their
study, which may have caused this conflict
between two studies.
A large sample size was the advantage of
this study, in which 564 human samples were
acquired. Nonetheless, this study contains various
limitations which might affect the image
interpretation. The resolutions of most images are
relatively low because the majority of these
patients presented to the clinic for implant
placement and maxillofacial pathology analysis. In
order to analyze small structures such as root canal
configuration efficiently, a different exposure
setting for higher image resolution are essential.
Even CBCTs has greater potentials
compared
to
conventional
2-dimensional
radiographs, they might not be used as a standard
routine for endodontic treatment in the present
dues to greater cost and higher radiation exposure
than necessary. Panoramic radiograph is a good
screening tool in the analysis of maxillofacial
structures and dentition, and it is often required to
be taken for the patient’s record. Jung et al. (2010)
conducted an experiment to compare the accuracy
of panoramic radiographs in the detection of
C-shaped canal to CT images. They concluded that
panoramic radiographs could be used for screening
to determine the need for further pre-operative
investigation before treatment, but it had less
sharpness compared to periapical radiographs. Due
to the nature of the study which was retrospective
study, panoramic images that used for
interpretation were reformatted from the CBCT
images. When compared with conventional
panoramic images, reformatted panoramic images
had more accuracy and less distortion. However,
false negative occurred in some cases, therefore
the clinicians should be aware of misinterpretation.
From the results of this study, despite the
statistically difference from the axial images,
panoramic images possessed high accuracy in
C-shaped canal detection. But there were mainly
seemed to be high probability in prediction for
those teeth with non-fused roots, while the ability
to detect C-shaped canal is lower.
Nowadays, CBCT technique has a crucial
role in dental treatment. In some countries, CBCT
is enrolled as standard imaging protocol for dental
diagnosis and treatment planning. Nevertheless,
CBCT is not a standard imaging protocol in
Thailand due to cost effectiveness and radiation
exposure.
6. Conclusion
CBCT images provide benefit for the
clinician in the accurate determination of various
Available online at www.rsu.ac.th/rjas
Rangsit Journal of Arts and Sciences, January-June 2015
Copyright © 2011, Rangsit University
RJAS Vol. X No. X, pp. C-1-C-5
ISSN 2229-063X (Print)/ISSN 2392-554X (Online)
root canal configurations.
Although the
reformatted panoramic radiography is not the
suitable substitution for CBCT in C-shaped canal
detection, but it could be used as another tool to
rule out the tooth without C-shaped canal
configurations. On the contrary, using panoramic
radiographs alone in C-shaped canal identification
is still not yet recommended.
International Endodontic Journal, 47(11):
1012-1033.
Silva E.J., Nejaim Y., Silva A.V., Haiter-Neto F.,
and Cohenca N. (2013). Evaluation of
Root Canal Configuration of Mandibular
Molars in a Brazilian Population by Using
Cone-beam Computed Tomography: An
In Vivo Study. Journal of Endodontics,
39(7): 849-852.
7. Acknowledgements
Assist.Prof. Chainut Chongruk, Director
of Radiology Department, Faculty of Dentistry,
Rangsit University.
Assist.Prof. Wichit Taranon, Director of
Advanced Dental Technology Center (ADTEC).
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