Abstract
OBJECTIVE: This study aimed to investigate the incidence of bifid mandibular canals (BMCs) using high-resolution MRI with a three-dimensional volumetric interpolated breath-hold examination sequence (3D-VIBE) through the neurovascular bundle (NVB). METHODS: In this retrospective study, we extracted 154 datasets from our archive of patients who underwent MRI examination with a 3D-VIBE sequence for mandible lesions from January 2015 to April 2016. The right and the left mandibles were treated independently with 59 cases excluded due to NVB morphology or artifacts, yielding 249 hemi-mandible cases classified among three subtypes: Type 0 with no BMC, Type one with one NVB and two NVBs on route to it, and Type two with two NVBs. We also investigated the incidence of nutrient canals (NCs) using MRI. Finally, we determined whether each BMC case could also be identified via panoramic radiography (PR) or CT. RESULTS: Of the 249 cases examined, 6.4% were found to have BMC (Types 1 and 2). Subtypes were classified as follows: 233 as Type 0 (93.6%), 11 as Type 1 (4.4%), and 5 as Type 2 (2.0%). The NC was identified on MRI in a majority of cases. No BMCs were identified using PR or CT except for one, which was identified by CT. CONCLUSION: The incidence rate of BMC per MRI was 6.4% in this study. NCs, including the retromolar canal, had an incidence rate of 58.4-97.6%. Further, BMCs were not verified by PR or CT, indicating that MRI should be used to assess BMCs.