C-shaped root canal system in mandibular second molars in a Chinese population evaluated by cone-beam computed tomography.

AIM To evaluate the anatomical features of C-shaped canal systems in Chinese mandibular second molars by cone-beam computed tomography (CBCT). METHODOLOGY A total of 608 patients of Chinese descent with healthy, well-developed mandibular second molars were enrolled. These patients were referred to the West China Hospital of Stomatology and required radiographic examination by CBCT as part of their routine dental treatment. Of the 608 examined CBCT images, 528 showed unilateral intact molars and 80 showed bilateral intact molars. Bilateral molar data were only used to analyse the distribution of unilateral and bilateral occurrences of C-shaped canals. The following in vivo CBCT observations were made: (i) frequency and type of root; (ii) frequency of C-shaped canals by gender, age and tooth position (left versus right); (iii) the classification of cross-sectional canal images of C-shaped canals; and (iv) unilateral and bilateral occurrences of C-shaped canals. RESULTS Fused roots were present in 39% of molars. A C-shaped canal system was present in 39% of the teeth. This prevalence did not differ with gender, age and tooth position. Most (81%) of the C-shaped canals in individuals with bilateral molars were symmetrical. Most of the canals with uninterrupted 'C'-shapes appeared to divide into two or more canals towards the canal terminus. CONCLUSION There was high prevalence of C-shaped canals in the mandibular second molars of Chinese population. The canal systems varied considerably in their anatomical configuration.