Evaluating Root Canal Morphology in Mandibular Second Molars of an Iranian Population Using Cone-Beam Computed Tomography

Abstract Background and Aim: Root canal morphology impacts endodontic success, yet data on mandibular second molars in the Iranian population is limited. This study aims to evaluate their root canal anatomy using Cone-Beam Computed Tomography, enhancing treatment planning and clinical outcomes in endodontics. Materials and Methods: This cross-sectional study utilized a convenient sampling method to analyze 221 Cone-Beam Computed Tomography (CBCT) images of mandibular second molars from an initial 718 scans taken between October 2013 and May 2014. Exclusions were made for previous root canal treatment, root resorption, periapical pathosis, calcified canals, post and core restoration, open apex, and low image quality. The study assessed root and canal numbers, canal shapes using the Vertucci classification, and C-shaped canals per the modified Melton method, while also evaluating the effects of age, gender, and bilaterality. The data were analyzed using the marginal homogeneity test and the exact Chi-Square test. The statistical software employed in this study was SPSS Software (Version 23.0, IBM Corp., USA) for Windows. Results: Most second mandibular molars had two roots (81.5%), with C-shaped roots observed in 6.9% of cases. Among those with separated roots, the predominant canal type in the distal root was Type I of the Vertucci classification (98%), followed by Type V (1.7%) and Type II (0.3%). The mesial root exhibited more variation, with Type III being the most common configuration (40.6%). Most cases on both sides had the same number of roots (81.6%), and two-rooted second molars predominantly had one canal in the distal root (95.6%). In both genders, two roots were found in most cases (male: 62.7%, female: 80.9%), and 80% of individuals over 50 had two-rooted second molars, with the highest prevalence of C-shaped roots in this age group (13.3%). Conclusion: The mandibular second molars in the studied Iranian population predominantly had two roots, with Type I being the most common configuration in the distal root (98%) and Type III in the mesial root (40.6%). The prevalence of "C-shaped canals was low (5.1%), highest in those over 50 (13.3%). No significant differences were found in root shape between genders or sides of the mandible.