上颌磨牙近中颊根第二根管的定位与扩通

目的　研究上颌磨牙近中颊根第二根管口 (secondmesiobuccalcanal,MB2 )与近中颊根管口 (mesiobuccalcanal,MB)、腭侧根管口 (palatal,P)的相对位置关系 ;探讨根管显微镜在上颌磨牙MB2治疗中的作用。方法　选取 1 1 3颗上颌磨牙 ,截去牙冠后肉眼寻找并扩通MB2根管 ,然后将未找到MB2或不能扩通的标本利用根管显微镜重复上述操作。对找到MB2根管的标本进行扫描 ,利用Image Proplus 4 .0图像分析软件分析MB2根管口与MB、P根管口的关系。结果　MB MB2距离为(1 47± 0 54)mm ,MB P距离为 (5 77± 0 66)mm ,MB2根管口与MB P连线的垂直距离为 (0 53±0 2 8)mm ,MB P连线与MB MB2连线的夹角 (α)为 2 3 0 7°± 1 3 0 8°。肉眼下有 70颗找到MB2根管口(61 9% ) ,其中 53颗通畅 (46 9% ) ;在根管显微镜下又有 6颗找到MB2 ,其中 4颗MB2根管通畅 ,MB2根管发现率提高 5 4% ;原MB2不通畅的根管又有 2颗通畅 ,MB2根管通畅率提高 5 4%。结论　MB2根管位于MB舌侧 2mm以内及MB P连线近中 1mm以内 ;上颌磨牙MB2发现率为 67 3 % ,其中52 2 %通畅 ;根管显微镜可以提高MB2的发现率及扩通率

Location and negotiation of second mesiobuccal canals in maxillary molars

OBJECTIVE: To investigate prevalence, location, negotiation and the effect of operating microscope (OM) in the treatment of the second mesiobuccal canal (MB2) in maxillary molars. METHODS: 113 maxillary molars were studied. The crowns of the teeth were removed 1 mm above the chamber bottom for searching MB2 canal. Initially location and negotiation of MB2 canal were attempted without OM. Teeth in which MB2 canal were not located or negotiated were further explored under OM. Canal orifices including MB orifice, MB2 orifice and palatal orifice were filled by red gutta-percha cones, then the teeth were scanned by scanner. The images were analyzed by Image-Proplus 4.0 software to measure the relationship between MB2 canal and other canals. RESULTS: The MB-MB2 distance is (1.47 +/- 0.54) mm, MB-P distance is (5.77 +/- 0.66) mm, the vertical distance from MB2 to MB-P line is (0.53 +/- 0.28) mm, the angle between MB-P line and MB-MB2 line is 23.07 degrees +/- 13.08 degrees. MB2 orifices were located in 70 teeth (61.9%) and negotiated in 53 teeth (46.9%) without OM. With OM, additional MB2 orifices were located in other 6 teeth, 4 were negotiated; and 2 were negotiated in which MB2 canal were not negotiated without OM. CONCLUSIONS: MB2 canal can be located in 67.3% and negotiated in 52.2% of maxillary molars. Ability to locate and negotiate MB2 canal is facilitated by OM. The MB2 canal was located less than 1 mm mesially to the MB-P line and 2 mm palatally from the MB orifice.