Imaging study of mandibular retromolar canal direction in Shanxi population

To study the morphological characteristics of the posterior canal of mandibular molars in the Shanxi population, provide theoretical guidance for the surgical safety of the retromolar region and mandibular ramus.

A total of 400 patients in the Department of Stomatology of the First Hospital of Shanxi Medical University were randomly selected to screen the images that met the inclusion criteria. Cone beam computed tomography and digital software were used to measure the relevant data. Divide the classification of the retromolar canal, and establish a three-dimensional model of the retromolar canal. The number, distribution and course of the retromolar canals were observed and counted, and the relevant data were measured.

A total of 368 samples were included in the study, and the retromolar canal was present in 84 samples, with an incidence of 22.83%. There were 47 men and 37 women; there were 55 on the left side and 52 on the right side, with no significant difference between the gender. In this study, the mandibular angle was bounded by the posterior margin of the retromolar region, and the initial position of the retromolar canal was divided into two regions: A (mandibular ramus area) and B (retromolar area). The retromolar canal can be divided into types A1 to A5 and B1 to B4 according to its shape and course, with type A3, which starts from the mandibular ramus area and bends upward along the medial side of the mandible, being the most common, followed by type B3, and type A4 being the least common. The mean length of the retromolar canal was (10.95 ± 2.76) mm, the mean diameter of the starting position was (1.22 ± 0.50) mm, the mean diameter of the retromolar foramen was (1.05 ± 0.39) mm, and the mean distance from the retromolar foramen to the distal enamel cementum boundary of the third molar was (9.50 ± 3.66) mm.

The incidence of retromolar canals is high in the population of Shanxi Province. It is necessary to note the presence of these canals in order to avoid intraoperative and postoperative complications when performing surgery on the retromolar region and mandibular ramus.