Cone-beam CT Study Of The Root And Root Canal Type In Mandibular Second Molar In Shandong

ObjectiveThe root canal system of the mandibular second molar tooth is more complicated and changeable than other tooth,and C-shaped canal is its major variation type.The early diagnosis and treatment of C-shaped canal contribute to the complete cleaning,appropriate formation and close packing of the root canal system.In this paper,the root canal morphologies of mandibular second molar teeth of Shandong people as well as the occurrence rate of C-shaped canal were observed and analyzed by using CBCT,expecting to provide reference for clinical diagnosis and treatment.MethodsThe image samples of patients undergoing CBCT examination in the department of stomatology,the Affiliated Hospital of Qingdao University were randomly selected.The inclusion criteria were as follows: bilateral mandibular second molar teeth exist,the teeth roots develop completely,and the dental bodies have no obvious carious lesion and do not receive root canal treatment.The statistically analysis of the root canal morphologies of the research was based on Melton classification method.ResultsThe CBCT image data of 615 cases/1230 mandibular second molar teeth were obtained.According to the statistics,the occurrence rate of C-shaped canal in mandibular second molar teeth was 40.5%(498/1230).The occurrence rate of left side was 7.6%(47/615),that of the right side was 8.9%(55/615),and that of double sides was 32.2%(176/1230).The occurrence rate of Melton Ⅰ was 21.5%(264/1230),that of Melton Ⅱ was 14.3%(176/1230),and that of Melton Ⅲ was 4.7%(58/1230).The left side and the right side showed no statistically significant difference in the occurrence rate of C-shaped canal(P>0.05),while there was a statistically significant difference between males and females(P<0.05).ConclusionThe number and type of root in mandibular second molar in Shandong are diversified.The C-shaped canal in mandibular second molar has a high occurrence rate,and it displays certain symmetry.The occurrence rate of C-shaped canal in mandibular second molar among males is higher than that among males;the occurrence rate of Melton Ⅰ is the highest,while that of Melton Ⅲ is the lowest.The height of pulp chamber decrease with ageing.