关键词: 锥形束 CT, 　下颌第1磨牙, 　根管形态, 　远舌根

Abstract:

Objective　To investigate the root canal configuration of mandibular first molars by using cone beam computed tomography (CBCT).　Methods　The CBCT imaging data of 500 patients, who were enrolled in Department of Stomatology, Nanfang Hospital between December 2014 and December 2015, were inspected by two endodontists. A total of 924 mandibular first molars were examined. The number of root, root canals and root canal configuration and the incidence of calcified canalwere observed and recorded. Statistical analysis was performed using Chi-squared test.　Results　The bilateral symmetry of root canal configuration is 76.2%(323). Among all the mandibular first molars, 76.7%(709) had double roots and 23.3%(215) had three roots, i.e. the incidence of distolingual root was 23.3%.  According to Vertucci’s classification, 71.97% (665) of the mesial roots were type IV, 23.70%(219) were type II; 49.35% (458) of the distal roots were type I, 31.82%(292) of them were type IV.When distolingual roots exist, the distance between root canal orifice of distolingual and distobuccal was (2.94±0.27) mm. The incidence of calcified canal in mandibular first molars was positively correlated with age.　Conclusion　The root canal configuration of the mandibular first molar in a southern Chinese subpopulation is various; CBCT is an effective tool for detecting additional distolingual roots and should serve as a favorable tool for diagnosis in root canal therapy for dental practitioners.

Key words: Cone-beam computed tomography;　Mandibular first molar;   , Root canal configuration;distolingual root