Anatomy of Permanent Mandibular First Molars in a Selected Iranian Population Using Cone-beam Computed Tomography

Introduction: Knowledge of radicular anatomy has a crucial impact on endodontic practices. Since some anatomic features such as modifications of Vertucci are not evaluated adequately, this study was conducted. Methods and Materials: In this in vivo study, cone-beam computed tomography (CBCT) images of 312 intact bilateral first molars from 156 patients (79 males and 77 females with an average age of 35.58±11.17 years) were investigated by a trained dentist in terms of number of roots, number of canals in each root and in each tooth, and shapes of canals according to Vertucci’s classification and its modifications. Groups were compared using the Chi-square test. The level of significance was set at 0.05. Results: Of all teeth, 5.2% had 3 roots. Mesial roots had mostly 2 canals while distal roots had a similar frequency of 1 and 2 canals. Of all teeth, 39.7% had 3 canals, 45.2% had 4 canals, 13.8% had 5 canals, and 1.3% had 6 canals. There were no significant differences between males and females, in terms of number of roots (P=0.137), number of canals in mesial (P=0.453) or distal roots (P=0.328), and total number of canals (P=0.138). The most frequent Vertucci classes in mesial and distal roots were IV followed by II and I, respectively. There were no significant differences between males and females in terms of Vertucci classes of mesial (P=0.211) or distal (P=0.205) roots. Conclusion: In this population, there were 3 to 6 canals per tooth (mostly 4 and 3 canals). Males and female’s might be similar regarding the number of roots, or number of canals in each root, number of canals in each tooth, or the predominant canal shape in each root.