Bifid variations of the mandibular canal: cone beam computed tomography evaluation of 1000 Northern Chinese patients.

OBJECTIVES: The aim of this study was to evaluate and quantify variations of bifid mandibular canals (BMCs) in a population of Northern China by using cone beam computed tomography (CBCT). STUDY DESIGN: CBCT images of 1000 consecutive patients were analyzed by using the NewTom proprietary software. BMCs were identified and classified on the basis of the Naitoh classification. Linear and angular measurements of BMCs were performed. Statistical analyses were conducted by using χ2 and Wilcoxon tests. RESULTS: BMCs were observed in 13.2% of 1000 patients and 8.4% of 2000 sides. The prevalence of BMCs was significantly lower in patients in the first 2 decades and in cases with a class II molar relationship. The retromolar canal (68.4%) was the most common type of BMC observed. No buccolingual canals were identified; however, 2 special canals were detected. A classification system of 3 subtypes of retromolar canals was suggested. On average, the beginning site of the branches from the opening of the main canal was at a distance of 8.1 mm. The mean diameter and length of BMCs were 2.1 mm and 12.6 mm, respectively. CONCLUSIONS: This study underlined the prevalence and characteristics of BMCs in a population of Northern China. Preoperative identification of BMCs with CBCT may help prevent postoperative complications.