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RESEARCH ARTICLE Open Access
Root canal morphology of permanent teeth in a Malaysian subpopulation using cone- beam computed tomography Julia Yen Yee Pan1, Abhishek Parolia2,5*, Siong Ren Chuah1, Shekhar Bhatia2, Sunil Mutalik3
and Allan Pau4
Background: To determine the root canal morphology of human permanent maxillary and mandibular teeth in a Malaysian subpopulation using cone-beam computed tomography (CBCT).
Methods: A total of 208 CBCT images were examined retrospectively. Prevalence of an extra root/canal and internal morphology based on Vertucci’s classification were observed in human maxillary and mandibular permanent teeth. Variations in the external and internal morphology were compared in relation to gender and tooth side (left vs right) using Pearson Chi-square and Fisher’s exact tests with significance level set at p < 0.05.
Results: In the maxillary arch, the prevalence of three canals were observed in 0.3% of first premolars and two canals in 46.5% of second premolars. Males displayed significantly higher prevalence of two canals in maxillary second premolars than females (p < 0.05). The prevalence of a second mesiobuccal canal in maxillary first and second molars were 36.3 and 8.5%, respectively. Males displayed significantly higher prevalence of a second mesiobuccal canal in maxillary second molars than females (p < 0.05). The prevalence of a second palatal canal in maxillary first and second molars were 0.9 and 0.6%, respectively. In the mandibular arch, the prevalence of two canals were observed in 5.1% of central incisors, 12.3% of lateral incisors, 6.1% of canines, 18.7% of first premolars and 0.5% of second premolars. The prevalence of a middle mesial canal, second distal canal and extra root (radix entomolaris) were detected in 1.9, 19.5 and 21.4% of mandibular first molars, respectively. The prevalence of a C-shaped canal was observed in 48.7% of mandibular second molars. Females displayed significantly higher prevalence of a C-shaped canal in the right mandibular second molars than males (p < 0.05). No other statistically significant differences in root anatomy and root canal morphology were observed in relation to gender and tooth side.
Conclusions: Wide variations in the root canal morphology exist among Malaysians. CBCT is a clinically useful tool in the identification of external and internal morphological variations in the human teeth.
Keywords: Cone-beam computed tomography, Malaysian, Morphology, Root canal
Background The success of an endodontic treatment requires a comprehensive knowledge of the root anatomy and root canal morphology along with its variations within the norm. In dental practice, the presence of anatomical aberrations in the root and root canal system may pose
a major endodontic challenge to clinicians. Therefore, thorough knowledge and understanding of their anatomy and variations is of utmost importance to avoid potential complications and undesirable failures during endodontic procedures . Globally, there are numerous studies [2–7] reporting
the internal and external morphological variations among different ethnicities. Only a few studies [8–11] had been conducted to evaluate the root canal morph- ology in a Malaysian population.
* Correspondence: email@example.com 2Division of Clinical Dentistry, School of Dentistry, International Medical University (IMU), Bukit Jalil, Kuala Lumpur, Malaysia 5Bukit Jalil, Kuala Lumpur, Malaysia Full list of author information is available at the end of the article
© The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Pan et al. BMC Oral Health (2019) 19:14 https://doi.org/10.1186/s12903-019-0710-z
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Abd Latib et al.  reported the prevalence of a sec- ond mesiobuccal canal in maxillary first molars among Malaysians was 18% for males and 10% for females. Choi et al.  compared the incidence of a second mesiobuc- cal canal in maxillary first molars between Caucasians and Malaysians. In that study, 65.44% of Malaysians were found to have two mesiobuccal canals . Bhatia et al.  reported the prevalence of radix molars in ex- tracted first molars among Malaysians was 4.9% whereby the prevalence of radix entomolaris (4.2%) was more common than radix paramolaris (0.7%). Besides that, an in vitro study by Nie et al.  reported that the occur- rence of C-shaped canal in mandibular second molars among Malaysians was 8 (3.3%) out of 241 cases or 88.8% of total number of mandibular molars. In that study, C-shaped canal was found to be more common in the Chinese race in which it was proven to be statisti- cally significant . Various methodologies have been employed to evaluate
the root and root canal morphology such as the use of clearing technique, cross-sectioning technique, analysis of extracted teeth, conventional radiography and cone-beam computed tomography (CBCT). With the advent of CBCT, many recent endodontic studies have been incorp- orating the three-dimensional approach as CBCT offers a wide array of advantages. CBCT permits modification of the visual field, yields a high resolution and produces a minimal amount of radiation as compared to conventional computed tomography . Furthermore, majority of the CBCT equipment are ergonomically designed for safe use and optimal performance . The present study therefore aimed to investigate the
prevalence of morphological variations in the root anat- omy and root canal morphology of human maxillary and mandibular permanent teeth in a Malaysian subpopula- tion using CBCT and to correlate the findings with gen- der and tooth side.
Methods Sample selection The present study consisted of 208 CBCT images of max- illary and mandibular permanent teeth that had been taken from patients who visited the Oral Health Centre at International Medical University (IMU) for diagnosis and preoperative assessment for implants, surgical extraction and orthodontic treatment. Written informed consents were obtained from patients whose images were used. Based on the previous studies [8–11] on Malaysian popu- lation, an expected frequency of 15%, an acceptable mar- gin of error of 5% and a design effect set at 1 with 95% confidence interval were used as parameters for Epi Info StatCalc statistical software (version 22.214.171.124) to calculate the total sample size. Epi Info is a trademark of the Cen- ters for Disease Control and Prevention.
Inclusion and exclusion criteria Healthy, untreated, fully developed, permanent maxillary and mandibular incisors, canines, first and second pre- molars and molars in individuals were included. Cases whereby anatomy was compromised by physiological or pathological processes and the original root anatomy was not clear, were excluded.
Pilot study Prior to the start of study, the researcher underwent train- ing from trained oral radiologist and endodontists on how to operate the CBCT and identify root canal morphology from CBCT images, respectively. The pilot study was car- ried out using 20 CBCT images whereby all observations were performed independently by the researcher, oral radiologist and endodontists. CBCT images were studied using the same computer and screen under ambient room lighting conditions. Inter-observer reliability test was car- ried out using Cohen’s Kappa test (< 0 less than chance agreement, 0.01–0.20 slight agreement, 0.21–0.40 fair agreement, 0.41–0.60 moderate agreement, 0.61–0.80 substantial agreement, and 0.81–0.99 almost perfect agreement) as proposed by Viera & Garrett . A final consensus was reached when the inter-rater agreement kappa value was found to be within the substantial agree- ment (0.61–0.80) or almost perfect agreement (0.81–099). Throughout the study, the calibration of the researcher was tested by repeating the observations twice on a ran- dom sample of 50 CBCT images.
Radiographic technique and image analysis The images for the study were selected from the data- base of KaVo 3D eXam imaging system (Imaging Sci- ences International, Hatfield, PA, USA). The images were acquired from a standard protocol for patient posi- tioning, exposure parameter setting (120 kVp, 5 mA, 26.9 s) and image acquisition of 0.25 mm voxel size. The images were analysed on eXam Vision software version 126.96.36.199 (KaVo Dental GmbH, Biberach, Germany). The axial, coronal and sagittal planes, as well as custom planes of the selected images were magnified to 150% to visualise the cross section of root canal morphology.
Measurements The variables evaluated were patient’s gender, age, ethnicity, tooth side, number of roots and root canal configuration. The canal configurations were categorized into the follow- ing eight types based on Vertucci’s classification :
1. Type I: A single canal extends from the pulp chamber to the apex.
2. Type II: Two separate canals leave the pulp chamber and join short of the apex to form one canal.
Pan et al. BMC Oral Health (2019)