The observation of bifid mandibular canals using cone beam computed tomography

To investigate the prevalence of bifid mandibular canals (BMC), and to measure their diameter and angle.

CBCT images of 500 patients were used for this study. The incidence and types of bifid mandibular canals were recorded according to a modified classification of Naitoh: Ⅰ, retromolar canal; Ⅱ, dental canal; Ⅲ, forward canal; Ⅳ buccolingual canal. The diameter and angle between the accessory canal and the main mandibular canal were recorded.

Bifid mandibular canals were found in 32.2% of the 1000 hemi- mandibles, with the incidence rate of 52.17%, 36.02%, 6.21%, 5.59% in Type Ⅰ, Ⅱ, Ⅲ, Ⅳ respectively. There are 90 cases of the mandibular branch with a diameter greater than or equal to the backbone 1/2, and 100 cases that are less than 1/2 of the backbone. The angle between the mandibular branch and the trunk Ⅰ, Ⅱ and Ⅲ were 50.21° ± 22.25°、28.81° ± 11.5° and 13.50° ± 2.39° respectively.

Bifid mandibular canals were observed at a relatively high incidence using CBCT, and the most common type was the retromolar canal. It is suggested CBCT should be taken before mandibular surgery to give an accurate evaluation of bifid mandibular canals.