Abstract: Objective: To evaluate the morphology of C-shaped root canal in mandibular second molars by CBCT. Methods: Digitized CBCT images from 579 subjects with C-shaped root canal in mandibular second molar were obtained. The incidence of symmetry, the root groove, and canal morphology in different cross sections were analyzed. Results: The incidence of symmetry was 80.0%. Four hundred and six mandibular second molars with C-shaped canal showed significant differences in the root canal configuration of root canal orifice, middle, and apical (P<0.05). There was statistical difference in the root canal configuration of middle and apical of root canal between males and females (P<0.05). There was statistical difference in the root canal configuration of three cross-sections between 18-25 and 26-50 age groups (P<0.05). There was statistical difference in the root canal configuration between the teeth with single lingual groove and with both buccal and lingual groove. Conclusion: Using CBCT can accurately determine the configuration and orientation of the C-shaped root canal of mandibular second molar, which helps diagnose and treat complex C-shaped root canals.

Key words: mandibular secondmolar, C-shaped root canal, cone-beam computed tomography