目的

探讨下颌第一磨牙近中根管的根管口形态特点和临床治疗方法。

方法

选取71 颗临床进行根管治疗的下颌第一磨牙，在手术显微镜下观察并记录近中根管的根管口形态，分类计数；采用Protaper 机用镍钛器械及超声器械进行根管预备，常规针式冲洗合并超声荡洗，热牙胶垂直加压充填技术充填根管；根据治疗前后临床检查及X 线片评价根管预备和充填的效果。

结果

所有样本中单根管口出现率为2.82%（2 例）、双根管口为91.55%（65 例）、三根管口为5.63%（4 例）。 其中双根管口之间有峡区的为38 例（53.52%）、无峡区的为27 例（38.03%）。 所有患牙根管治疗后均无根管内并发症发生，术后1 年根管治疗成功率为92.9%。

结论

下颌第一磨牙根管形态复杂，手术显微镜有助于根管形态的探查，机用镍钛器械合并超声技术预备根管，超声冲洗和热牙胶垂直加压技术充填根管可获得良好的治疗效果。

Objective

To identify the morphology characteristic of root canal orofices in the mesial canal of mandibular first molars using operating microscope， and to.

Methods

The mesial canals in 71 mandibular first molars were counted and detected by operating microscope. The root canals were shaped by using Protaper rotary instruments and ultrasonic instruments， cleaned by needle irrigation and ultrasonic irrigation with sodium hypochlorite， and obturated with warm gutta-percha by vertical condensation technique. The efficiency of preparation and obturation was analyzed with radiographs before and after operation.

Results

2 molars were found to have single root canal orifice （2.82%）， 65 molars were found to have two roots canal orifice （91.55%）， 4 molars were found to have three roots orifice （5.63%）. 38 cases have isthmus between mesiobuccal and mesiolingual root canals （53.52%），27 cases have no isthmus （38.03%）. There was no any complication in all cases. The treatment success rate after one year of treatment is 92.9%.

Conclusions

The morphology of mandibular first molar is complex， and the operating microscope is considered to be helpful in identification of the root canal morphology of mandibular first molars. The rotary nickel-titanium instrumentation， ultrasonic irrigation with sodium hypochlorite， and vertical condensation technique can obtain good treatment effect.