THE VARIETY OF ROOT AND CANAL MORPHOLOGY OF MAXILLARY SECOND MOLARS BY CONE-BEAM COMPUTED TOMOGRAPHY IN A NORTHWESTERN CHINESE POPULATION

Objective: To investigate variety of root canal system of maxillary second molars in a northwestern Chinese population using cone-beam computed tomography (CBCT). Materials and Methods: 913 maxillary second molars from 496 CBCT images were enrolled. The number of roots and canals, canal configuration, root morphology, location of the second mesiobuccal (MB2) canals and symmetry in homonym teeth were recorded. Canal configuration was classified by Vertucci's classification. Results: Totally 913 maxillary second molars, a higher prevalence of three roots (86.64%) and three canals (77.98%) was present. The incidence of MB2 canals was 10.84%, and the most prevalent configuration of the mesiobuccal (MB) canal when MB2 was present was type II (81.82%). MB2 was 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 was 69.55%, 21.14%, and 9.31%, respectively. There was a significant difference of the symmetry between different numbers of root on root canal system(p<.001). Conclusion: The canal system of maxillary second molars was variable in a northwestern Chinese population. The most common form of the variety was MB2 canal, which had a constant position to locate. The variation of four roots may increase the difficulty of endodontic therapy. CBCT could enhance the understanding of root canal anatomy to improve the outcome of endodontic treatment.