Mandibular second molar root canal morphology and variants in a Korean subpopulation

Aim: To determine the root canal anatomy of mandibular second molars in a Korean population by analysing cone-beam computed tomography (CBCT) images. Methodology: The CBCT images of 960 subjects were examined. The number and configuration of roots and canals were categorized according to Vertucci's and modified Melton's classifications. Results: Of the 1920 mandibular second molars, 41% had one root, 58% had two roots, and <1% had three roots. In the mesial roots of two-rooted molars, Vertucci's Type lV (44%) and Type II (37.75%) canals were most frequent. The prevalence of C-shaped roots was 40%, and C-shaped roots in combination with additional mesiolingual or distolingual roots were found in <1% of molars. Interestingly, O-shaped canals were detected in 0.10% of the molars. Of the C-shaped roots, the most common configuration types were Melton's Type I (66%) in the coronal region and Melton's Type III (56%) in the apical region. The prevalence of C-shaped roots was higher in females (47%) than in males (32%) (P < 0.001) and did not differ with age (P = 0.497) or tooth position (P = 0.514). Most (82%) C-shaped canals were bilateral (P < 0.001). Conclusions: A high prevalence of C-shaped canals and a low incidence of three-rooted molars were observed in the mandibular second molars of the Korean subpopulation studied.