C-shaped canal configuration in mandibular second molars of a selected Uyghur adults in Xinjiang: prevalence, correlation, and differences of root canal configuration using cone-beam computed tomography.

Objectives: To determine the prevalence of C-shaped root canal system configurations and assess the correlation between C-shaped root canal prevalence and root morphology in mandibular second molars among adults in Xinjiang Uyghur population using cone-beam computed tomography (CBCT).

Materials and methods: CBCT imaging data from patients treated at the First Affiliated Hospital of Xinjiang Medical University (Affiliated Stomatology Hospital) were retrospectively analyzed. The prevalence of C-shaped root canal configurations in mandibular second molars was determined based on Fan et al.'s classification. Axial sections of each tooth were evaluated in the coronal, middle, and apical thirds to identify canal configurations and analyze root morphology. The differences in C-shaped canal prevalence between genders and tooth positions were compared. Statistical analysis was performed using the chi-square test (p < 0.05).

Results: A total of 1748 patients were included, with 510 (29.17%) exhibiting C-shaped root canals. Females exhibited a higher prevalence (31.49%) than males (25.15%). C-shaped canals were more frequently observed on the lingual surface (76.8%) than the buccal surface (22.2%). Bilateral symmetry of C-shaped canals was observed in 64.7% of cases. A significant association was found between C-shaped canals and root morphology (p < 0.001). Among patients with C-shaped canals, 66.9% demonstrated symmetrical configurations. The most common configuration was C3 (present in all axial levels), followed by C1 and C2. Mandibular second molars with three roots or type 3/type 4 morphologies exhibited a high probability of C-shaped canals.

Conclusions: C-shaped canals were more prevalent in females and lingually positioned in mandibular second molars. Bilateral C-shaped canals were frequently symmetrical and more common than unilateral cases. Mandibular second molars with three-root or type 3/type 4 morphologies may indicate a high likelihood of C-shaped canals. The most common configuration was C3, followed by C1 and C2, all present across all axial levels. Understanding these anatomical variations preoperatively can improve clinical management.