Anatomical and radiographic study of the mandibular retromolar canal

As the demand for surgical procedure in the retromolar area of the mandible has been increasing, the identification of the retromolar foramen (RMF) and canal involving the retromolar triangle (RMT) has become an issue of clinical concern. We examined the shape of the RMT, incidence of the RMF, and intraosseous trajectory of the retromolar canal (RMC).

A total of 118 sides of dry mandibles, 22 sides of mandibles of 13 cadavers, and cone-beam computed tomography (CT) images of 100 patients were examined. Micro-CT data of 13 cadavers were reconstructed using imaging analysis software for the presence of an RMC. RMCs were classified into three types according to the courses. The width and location of the RMCs were evaluated.

The shape of the RMT was classified into three categories, with the most common type being the triangular type (81.4%). Forty-seven retromolar foramina (33.6%) were observed in 140 sides of mandibles. The horizontal distances from the RMF to the second and third molars were 12.1 ± 3.3 mm and 5.8 ± 3.6 mm (mean ± standard deviation), respectively, and the distance from the mandibular foramen to the arising point of the RMC and the vertical distance from the RMF to the mandibular canal were 21.5 ± 11.2 mm and 15.3 ± 4.6 mm, respectively.

This study used various methods to obtain precise anatomical data on the RMT, foramen, and canal in Koreans. The reported findings may be helpful for the clinical management of patients.