Evaluation of root canal morphology of mandibular premolars in Pakistani population using the new classification: a CBCT study

Abstract

Background: A comprehensive understanding of the root form and canal anatomy is essential for successful endodontic treatment. This study aimed to evaluate the root canal anatomy of mandibular premolars in the Pakistani population using cone beam computed tomography (CBCT) and to classify the findings with the new classification proposed by Ahmed et al. METHODS: Ethical exemption was obtained from Aga Khan University Hospital, Karachi. A total of 707 CBCT scans from Karachi and Lahore were included, comprising 592 scans from a tertiary care hospital in Karachi and 115 scans from a radiology center in Lahore. The study focused on sound, fully formed mandibular first and second premolars, excluding those with significant caries, restorations, or prior root canal treatments. Scans from different equipment were used, and calibration was achieved between a specialist endodontist and two dental residents. Data was analyzed using the Statistical Package for the Social Sciences (SPSS) software, version 26. Descriptive statistics, Chi-square tests to determine association between the variables, and a significance level set at 5% (p <0.05) were utilized.

Results: A total of 2403 mandibular premolars were analyzed. The most common configuration was ¹MPM¹ (82.90%), with rare variations such as ¹MPM^1-3-1 (0.04%) and ²MPM^{1 B1 L2} (0.04%). Single-rooted premolars were predominant (98.87%), and no significant differences were observed when data was stratified by age or gender.

Conclusions: This is the first study in Pakistan involving multiple centers and using the classification system by Ahmed et al. to understand the anatomy of mandibular premolars. The findings indicate that while most premolars have a single root and canal, variations exist. These variations highlight the importance of understanding canal morphology for improving the success of endodontic treatment. Future studies should include a larger and more diverse dataset to fully represent the Pakistani population.

Keywords: CBCT; Mandibular premolars; Root canal anatomy; Root canal variations.

Fig. 1

The new classification system used to categorize the endodontic anatomy of the left mandibular second premolar. The assigned code (¹35¹) has three components. The number in the center (35) denotes the tooth number according to the FDI tooth numbering system. The superscripted number on the left denotes the number of roots of the tooth, whereas the superscript on the right denotes the canal configuration from its start, its course along the root till its exit from the apical foramen. (Created with BioRender.com)

Fig. 2

Flow chart depicting the selection of CBCT scans and the final inclusion of mandibular premolars for the study

Fig. 3

Mandibular premolars root and canal distribution

Fig. 4

A) Sagittal and axial views of mandibular premolars showing a single canal with a single exit. B) & C) Sagittal and axial views of the right mandibular first premolars showing some of the rare variations

Fig. 5

Distribution of mandibular premolars according to number of roots

Fig. 6

CBCT images in sagittal and axial sections showing left & right mandibular premolars exhibiting two roots and canals

Fig. 7

Sagittal and axial views of images showing single rooted mandibular premolars with two separate canals

Fig. 8

CBCT images in different sections showing mandibular premolars with a single canal splitting into two and then merging to form one canal again before exiting the tooth