目的　应用锥形束 CT(cone beam computed tomography，CBCT)观察下颌第1磨牙的根管解剖形态，为临床根管治疗提供参考依据。  方法　由两名牙体牙髓专业医生筛选我院口腔科自2014年12月至2015年12月进行 CBCT 检查的500名患者，共计924颗下颌第1磨牙的影像资料，分别记录患者的基本信息、牙位、根管构型及钙化情况，并进行统计学分析。   结果　424名存在双侧下颌第1磨牙的患者中，76.2%(323)根管构型完全对称。924颗下颌第1磨牙中，双根率为76.7%(709)，3根率即远舌根发生率为23.3%(215)；近中根最常见根管类型为Vertucci IV型，占 71.97%(665)，其次为II型，占23.70%(219)；远中根最常见根管类型为I型，占 49.35%(458)，其次为IV型占31.82%(292)。存在远舌根时，远舌根管口与远颊根管口距离为(2.94±0.27) mm。下颌第1磨牙根管钙化率与年龄有关，老年人钙化率高，中年人次之。  结论　华南地区人群下颌第1磨牙根管形态多样，变异性较大；CBCT 是观察根管形态的有效工具,可以为根管治疗提供辅助诊断。

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.