上颌恒磨牙近中颊根根管弯曲情况的离体研究

The extra corporeal study of curvature frequency in the mesiobuccal root canal of maxillary molars

目的 分析上颌恒磨牙近中颊根根管分型、弯曲发生情况、弯曲位置、弯曲方向及弯曲程度。方法 收集上颌第一、第二恒磨牙 6 0颗 ,探查近中颊根管 ,并于根管内插入 0 0 6 #～ 0 15 #扩大针 ,拍摄颊舌向 (临床 )和近远中向 (邻面 )X -线片。用Photoshop - 6 .0软件分析根管弯曲位置、弯曲方向和弯曲角度。结果 ①上颌第一恒磨牙近中颊根MB1根管的发现并探通率为 90 .6 % ;MB2根管的发现并探通率为 71.8% ,近中颊根以 2 - 2型为主(4 8.2 7% ) ;上颌第二恒磨牙近中颊根MB1根管的发现并探通率为 89.3% ;MB2根管的发现并探通率为 6 0 .7% ,近中颊根以 2 - 1型为主 (4 8% )。②大多数MB1与MB2根管在两个观察方向均有不同程度的弯曲。第一弯曲多发生于根中 1/ 3及其冠方 ,临床片所示近颊根管多向远中弯曲 ,邻面片观察到的根管多向腭侧弯曲。在颊舌向发生的弯曲中 ,2 - 1型的MB2根管较MB1根管有更大的弯曲度 ;而 2 - 2型的MB1与MB2根管弯曲度无显著性差异 ;2 - 1型的MB2根管弯曲的发生率与弯曲度均高于 2 - 2型的MB1根管。在近远中向发生的弯曲中 ,2 - 1型的MB1根管弯曲度高于 2 - 2型的MB1根管。③第二弯曲多发生于根尖 1/ 3(部分发生于根中 1/ 3) ,弯曲度与第一弯曲度无显著性差异。结论 上颌第一。

Objective To analysis the classification,curvature frequency,position,direction and degree of mesiobuccal root canals of the maxillary molars.Methods Sixty randomly selected first and second maxillary molars were used in this study.Radiograph of teeth in buccolingual (clinical) and mesiodistal (proximal) directions with 006#～015# reamers in mesiobuccal root canals were taken.The curvature position,direction and angulations were calculated and recorded for both views using Photoshop- 6.0 by computer.Results ①MB2 root canals were found out by the rate of 71.8% and type 2-2 was the major sort ( 48.27%) of the mesiobuccal root canals in first maxillary molars.compare with 60.7% MB2 root canals were found out and type 2-1 is the major sort ( 48%) of the mesiobuccal root canals in second maxillary molars.②Mojority of MB1 and MB2 root canals showed curvatures at varying degrees in both views.The first curvatures always occurred in the middle 1/3 root region and its crown side.Distal and lingual directions were the common curvature direction of the first curvature.In buccolingnal direction,MB2 root canal showed greater curvature than MB1 in type 2-1.There is no difference of curvature degree between MB1 and MB2 root canals in type 2-2.The curvature rate and degree of MB2 root canal in type 2-1 were more greater than MB2 root canal in type 2-2.In mesiodistal direction,the curvature degree of MB1 root canal in type 2-1 were more greater than MB1 root canal's in type 2-2.③The secondary curvature was often found out in the apical 1/3 region(some were seen in the middle 1/3 region).There were no significant difference of degree between the first and second curvature.Conclusion The majority of mesiobuccal root canals in maxillary molars showed curvatures at varying degrees.