Anatomical and radiographic study of the mandibular retromolar canal

Abstract

Background/purpose 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). Materials and methods 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. Results 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. Conclusion 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.

Investigation of the Prevalence of Retromolar Canals: A Cone Beam CT Study

“…The diversity between the dry mandible and fresh cadaver studies can be explained with the RMF being lost due to the atrophic changes in dried bone (Motamedi et al). Park et al (2016), reported that the prevalence of RMF was 33.6 % according to macroscopic examination of cadaver mandibles whereas the prevalence of RMF/RMC on CBCT was 11.5 %. They concluded that the ability to detect an RMC using CBCT is limited compared with direct anatomical observation.…”

“…The RMC is positioned within or around the retromolar triangle (Park et al, 2016), branches from the main mandibular canal below the third molar and follows a recurrent path, curving in an anterior-superior direction behind the third molar to open in the retromolar foramen (RMF) (Ossenberg, 1987). The RMF is also found in the retromolar trigone, posterior to the last molar (Han & Park).…”

“…The RMC has a neurovascular bundle which is found to contain predominantly thin myelinated nerve fibers, numerous venules and arterioles covered by collagen bundle fibres and a little amount of adipose tissue (Alves & Deana, 2015;Capote et al, 2015;Han & Park;Lizio et al;Motamedi et al;Park et al;Potu et al). The artery in the RMC is the branch of inferior alveolar artery and the nerve derived from the inferior alveolar nerve (Kodera & Hashimoto, 1995;Capote et al).…”

“…There are important surgical procedures in the posterior region of the mandible such as insertion of dental implant, sagittal split osteotomy, bone harvesting procedures, and removal of impacted third molar (Bilecenoglu & Tuncer;Naitoh et al, 2009;Park et al;Patil et al). Bilecenoglu & Tuncer reported mean distances of 4.2 mm and 11.9 mm from the RMF to the distal aspect of the alveolar socket of the third and second molars, respectively.…”

Incidence and Anatomical Properties of Retromolar Canal in an Iranian Population: A Cone-Beam Computed Tomography Study

“…Several studies have reported different types of retromolar canals varying in their origin, course, and exit location [12][13][14][15][16][17][18].…”