Farzaneh Ostevar Rad
Elnaz Mousavi
Naghmeh Musapoor
Dina Maleki
Nikoo Khatibi

Background: Lack of knowledge of root anatomy is the second most common reason for failed endodontic therapy. Therefore, acquiring knowledge about it leads to a more effective treatment. C-shaped canal is an anatomical variation that causes clinical challenges. The objective of this study is to determine the occurrence of the C-shaped roots in permanent anterior and posterior teeth of the Iranian population using CBCT (cone beam computed tomography) scans. Methods: This was a descriptive cross-sectional study. In this study, ۱۴۰۸ teeth were assessed. Cranex ۳D Mid was used to prepare CBCT images. Each tooth was examined in axial sections, and five different levels were identified as coronal, medium, apical, ۱/۳, and ۲/۳. The canal shapes were classified into ۵ categories based on modified Melton’s method. Data were analysed using the chi-square test at a significance level of ۵%in SPSS version ۲۴.۰. Results: In total, of ۱۴۰۸ teeth which were evaluated, ۷.۸۱% (۱۱۰) were confirmed to have C-shaped canals. The occurrence of the C-shaped canal was significantly higher in molars (P < ۰.۰۰۱). The occurrence of the C-shaped canal was significantly higher in mandibular teeth (۱۰.۰۴%) compared to maxillary teeth (۵.۸۱%) (P < ۰.۰۰۱). The most common C-shaped canal category was C۱ (۵۷.۲۷%). The relationship of gender and age with the C-shaped canal occurrence was not statistically significant (P = ۰.۵۸۵, P = ۰.۵۶۲, respectively). Conclusions: CBCT is a useful tool to evaluate C-shaped root canal morphology. The high occurrence of the C-shaped canal in the Iranian population requires clinical awareness.