| Objective:The purpose of this study was to observe the morphological characteristics of mandibular retromolar canal in adults in Shanxi region,determine the incidence of retromolar canal and explore the relationship between the incidence of retromolar canal and related measurements with gender,jaw side and age groups by using cone beam CT and digital software.This study also divided the three-dimensional typing of retromolar canal for the first time.These results can provide theoretical guidance for the safety of surgery in the retromolar area and mandibular ramus area.Methods:The system randomly selected 500 CBCT images of patients from the Department of Stomatology of the First Hospital of Shanxi Medical University from January 2020 to December 2021 from various cities in Shanxi Province after screening by the inclusion and exclusion criteria.The images were imported into the Mimics 21.0 and SIMPLANT PRO 17.01 software in Digital Imaging and Communications in Medicine format and then the retromolar canal were observed,the number and incidence of retromolar canal were counted,the linear distances between the relevant loci of retromolar canal were measured,the three-dimensional models of retromolar canal were established,and the data were statistically analyzed.Results:Of the 500 samples in this study,112 samples had retromolar canals,with an incidence of 22.40%.There were 48 males and 64 females;there were 73 on the left side and 66 on the right side;There were 47 cases in the youth group,57 cases in the middle-aged group,and 8 cases in the elderly group,with no statistically significant difference in the incidence of retromolar canal between sex,side and age groups.In this study,the starting position of the retromolar canal was divided into two areas,A(mandibular ramus area)and B(retromolar area),the mandibular angle and posterior margin of retromolar area were used as the boundary,and the retromolar canal was divided into 9 types,A1 ～ A5 and B1 ～ B4,according to the morphology and course.The horizontal length of the retromolar canal was 10.93(9.69,12.31)mm,the vertical height of the retromolar canal was 11.04(9.35,12.72)mm,and the distance of the retromolar foramen from the cementoenamel junction of the third molar far middle was 7.77(6.33,9.38)mm.The horizontal distance between the center point of the starting position of the retromolar canal and the buccal bone wall was 6.69(5.74,7.71)mm,the horizontal distance between the center point of the starting position of the retromolar canal and the lingual bone wall was 3.63(3.08,4.59)mm,and the difference in the horizontal distance between the center point of the starting position of the retromolar canal and the buccolingual bone wall was statistically significant.The vertical distance between the center point of the retromolar foramen and the buccal bone wall was 8.65(7.58,9.96)mm,the vertical distance between the center point of the retromolar foramen and the lingual bone wall was 4.20(2.99,5.59)mm,and the differences in the vertical distance between the center point of the retromolar foramen and the buccolingual bone wall were statistically significant.The diameter of the retromolar canal starting position was 1.13(0.94,1.40)mm and the diameter of the retromolar foramen was 0.75(0.61,0.95)mm,and the differences between the diameter of the retromolar canal starting position and the diameter of the retromolar foramen were statistically significant.The differences in retromolar canal measurements between lateral and age groups were not statistically significant,but there were statistically significant differences in the horizontal length of the retromolar canal,vertical height,and distance of the retromolar foramen from the cementoenamel junction of the third molar far middle between males and females.Conclusion:The incidence of retromolar canal in adults in Shanxi region was 22.40%,and the incidence was not related to gender,jaw side and age.The retromolar canal in adults in Shanxi region could be divided into A1～A5 and B1～B4,totaling 9 types.Among the various subtypes of retromolar canal,type A3 was the most common,followed by type B3,and type A4 was the least common.The retromolar canal in adults traveled medially to the mandible in Shanxi region.The morphological characteristics of the retromolar canal in adults in Shanxi did not differ significantly between jaw side and age groups,and the differences between the sexes were considered to be due to different jaw development in males and females.The incidence of retromolar canal is relatively high in adults in Shanxi area.CBCT examination should be performed before surgery in the retromolar area and mandibular ramus area to determine the morphology and location of retromolar canal,so as to avoid intraoperative and postoperative complications. |
PDF Full Text Request