离体上颌磨牙近中颊根第二根管出现率的研究

An in vitro study on the incidence of the second mesiobuccal canal in the mesiobuccal root of the first and second maxillary molars

目的运用透明标本观察法、螺旋 CT 薄层扫描技术和牙根硬组织切片观察法研究中国人离体上颌第一、二磨牙近中颊根第二根管(MB2)的出现率。方法分别收集离体上颌第一磨牙216例、第二磨牙334例,均随机分为两组:A 组制成透明标本;B 组标本经螺旋 CT 扫描后,自根尖开始每隔1 mm 横切牙根。所有离体牙标本均在牙科手术显微镜下观察并记录近中颊根的根管数目。结果透明标本观察法所得的上颌第一、第二磨牙 MB2出现率分别为81.48%和49.70%;螺旋 CT扫描技术所得的结果分别为77.78%和47.31%;牙根硬组织切片法所得的结果分别为88.89%和53.89%。上颌第一磨牙 MB2出现率高于第二磨牙,其差异有统计学意义(P<0.05)。同一牙位不同实验方法间的结果差异均无统计学意义(P>0.05)。结论上颌第一、二磨牙 MB2出现率高,提示临床医师应努力探查该根管,以提高上颌磨牙根管治疗的成功率。

Objective To investigate the incidence of the second mesiobuccal canal （MB2） in the mesiobuccal root of the maxillary first and second molars in Chinese population using three techniques, including the clearing technique, spiral CT scanning and serial root sections. Methods A total of 216 extracted human first and 334 second maxillary molars were randomly divided into two groups respectively： group A and B. The teeth in group A were cleared. The specimens in group B were subjected to spiral CT scanning, and then the roots were cross-sectioned every 1 mm from the root apex. Under the Dental operating microscope（DOM）, the incidence of MB2 were recorded. Results ① The incidence of MB2 in the first and the second maxillary molars were 81.48% and 49.70% respectively by clearing, and 77.78% and 47.31% from S-CT scanning, 88.89% and 53.89% respectively from serial root section. The occurrence of MB2 in maxillary first molars was statistically higher than in maxillary second molars （ P 〈 0.05, chi square test）. ②There was no significant difference among the three approaches for detecting the MB2 canal （P 〉 0. 05, chi square test）. Conclusions Both the maxillary first molars and the second molars have high incidence of MB2.