目的探讨上颌第一磨牙近颊第二根管(second mesiobuccal canal,MB2)的特征及临床治疗方法。方法选取患牙髓炎或根尖周炎的上颌第一磨牙95颗,拍摄术前X线片,术中采用小号K锉配合15%EDTA溶液探查根管,记录根管数目、形态和类型;采用机动镍钛器械Hero 642进行根管预备,侧向加压充填技术充填根管。结果上颌第一磨牙MB2的发现率为81.1%,扩通的MB2占72.6%,多数MB2根管细小弯曲,需用小号K锉配合使用EDTA进行疏通,机动镍钛器械预备根管无明显并发症。结论上颌第一磨牙MB2的发生率高,多数根管细小弯曲,小号K锉配合EDTA疏通根管,机动镍钛器械预备可获得良好的治疗效果。 Objective To investigate the characteristics and clinical treatment of second mesiobuccal canal (MB2) in maxillary first molars. Methods 95 maxillary first molars with pulpitis or periapical periodontitis were selected. The preoperative radiographs were taken. The root canal was probed with a small K file and a 15% EDTA solution. The number, shape and type of root canal were recorded ; Use of motor NiTi equipment Hero 642 for root canal preparation, filling the lateral pressure filling technology root canal. Results The detection rate of maxillary first molar MB2 was 81.1% and extended MB2 was 72.6%. The majority of MB2 canals were small and curved. They needed to be dredged with small K file and EDTA. No obvious complications disease. Conclusions The incidence of MB2 in the maxillary first molar is high, most of the canals are small and bended. The small K-file combined with EDTA to clear the root canal can provide a good therapeutic effect for the preparation of the mobile Ni-Ti instrument.