目的

探讨上颌磨牙近中颊根第二根管（MB2）的临床检出率以及手术显微镜在提高上颌磨牙临床检出率中的作用。

方法

选取进行常规根管治疗的63 颗上颌第一磨牙，27 颗上颌第二磨牙，以及进行显微根管治疗的55 颗上颌第一磨牙，20 颗上颌第二磨牙，2 颗上颌第三磨牙，分别拍摄术前X 线片，探查根管，记录根管数目。

结果

进行常规根管治疗的上颌第一磨牙和上颌第二磨牙，MB2 检出率分别为28.6%和3.7%；进行显微根管治疗的上颌第一磨牙和上颌第二磨牙，MB2 检出率分别是61.8%和25%；对上颌第一磨牙常规根管治疗和显微根管治疗的MB2 临床检出率进行卡方检验，χ²=13.17，差异有统计学意义（P ＜0.001）；对上颌第二磨牙常规根管治疗和显微根管治疗的MB2 临床检出率进行Fisher 确切概率值检测，单侧比较值为0.043，差异有统计学意义（P ＜0.05）。

结论

手术显微镜有助于提高上颌磨牙MB2 的临床检出率，选择显微根管治疗有助于提升上颌磨牙根管治疗的成功率。

Objective

To investigate the clinical incidence of second mesiobuccal canal（MB2） in maxillary molars and the effect of dental operating microscope on locating the MB2 canal.

Methods

63 maxillary first molars， 27 maxillary second molars treated without microscope and 55 maxillary first molars， 20 maxillary second molars， 2 maxillary third molars treated with microscope were examined. Each case was taken preoperative X ray-film， explored by small size K files and record the number of canals.

Results

The incidence rate of MB2 was 28.6% and 3.7%in maxillary first molars and maxillary second molars treated without microscope. The incidence rate of MB2 was 61.8% and 25% in maxillary first molars and maxillary second molars treated with microscope. The incidence rate of MB2 in maxillary first molars between two treatment groups were significant different based by Chi-square analysis （P ＜0.001）. And the result of incidence rate of MB2 in maxillary second molars between two treatment groups were significant different based by Fisher exact probability test（P ＜0.05）.

Conclusion

Identification of the MB2 in maxillary molars is improved by microscope. More emphasis should be placed on the importance of using microscope for locating the MB2 canals.