A Lanzhou District Study On The Variety Of The Root And Root Canal Morphology Within Maxillary Second Molars Using Cone-beam Computed Tomography

Objective:To investigate variety of root canal system of maxillary second molars in lanzhou district using cone-beam computed tomography(CBCT).Methods:913 maxillary second molars from 496 CBCT images were enrolled. Root number and morphology, canal number and configuration, location of the second mesiobuccal(MB2) canals,distance of pulp chamber, and symmetry in homonym teeth were recorded. Software KaVo3 DeXam Vision 1.9 and Invivo 5 were used to scan and measure the images. Canal configuration was classified by Vertucci’s classification. Statistical analysis was performed using SPSS 20.0software.Results:Totally 913 maxillary second molars, a higher prevalence of three roots(86.64%) and three canals(77.98%) are present. The incidence of MB2 canals is 10.84%, and the most prevalent configuration of the mesiobuccal(MB) canal is type Ⅱ(81.82%) when MB2 canal is present.MB2 canal is located 2.03±0.42 mm mesially to MB canal, and may be a constant position to locate. The incidence of separate roots, fusion of any two roots, and three fused roots are 69.55%,21.14%, and 9.31%, respectively. There is a significant difference of the distance of pulp chamber,which decreases with the increasing ages(p < 0.01).There is a significant difference of the symmetry between different numbers of root on root canal system(p<.001).Conclusion:The canal system of the maxillary second molars is variable in Lanzhou district. The most common form of the variety is MB2 canal, which has a constant position to locate. The variation of four roots may increase the difficulty of endodontic therapy. CBCT may enhance the understanding of root canal anatomy to improve the outcome of endodontic treatment.