摘要
目的 :定量描述恒牙根分叉度的大小及其意义。方法 :从 15 0 0 0个离体牙中挑选出上、下颌第一和第二磨牙 40 0个 ,将其外形印痕至座标纸上 ,然后顺牙根外形印痕长轴作线使之尽可能重合 ,继而测量其线段构成的夹角 ,从而间接获得牙根分叉度值。结果 :①上颌第一磨牙两颊根分叉度平均为 14.5°± 8.3°;近中颊根与腭根分叉度平均为 30 .8°± 8.3°。②上颌第二磨牙两颊根间只有 2 8%存在分叉夹角 ,且平均为12 .1°± 2 .8°;近中颊根与腭根分叉度平均为 19.6°± 6 .8°。③下颌第一磨牙近远中根分叉度平均为 11.5°± 3.5°。④下颌第二磨牙只有 40 %的样本存在根分叉夹角 ,且平均为 10 .5°± 3.3°。结论 :①承受牙合力越大的牙齿其根分叉度也越大 ;②上下颌同名牙 ,由于受力方向存在差异 ,根分叉度也存在显著差异 ;③牙脱位难度是第一磨牙难于第二磨牙、上颌牙难于同名下颌牙。
AIM:To survey molars roots separate degree and explore their physiological importance. METHODS: 400 molars from stomatological hospital were researched (maxillary first and second molars 200, mandibular first and second molars 200 ). The appearance of tooth was printed on papers with oil ink firstly. Then the line was drawn along dental root long axis. Finally the angle between two root axis lines was measured with protractor. The measures were counted and estimated. RESULTS: ①The angle between medical and distal buccal roots of the first maxillary molars was 14.5°±8.3°(mean); the angle between mediobuccal and palatal roots of the first maxillary molars was 30.8°±8.3°(mean). ②There was only 28% of the second maxillary molars formed angle, the angle between medical and distal buccal roots was 12.1°±2.8°(mean), the angle between mediobuccal and palatal roots of the second maxillary molars was 19.6°±2.8°(mean). ③ The angle between medical and distal roots of the first mandibular molars was 11.5°±3.5°(mean). ④ There was only 40% of the second mandibular molars formed angle, its mean was 10.5°±3.3°(mean). CONCLUSION: ① The more occlusal force, the separeted angle between roots is larger. ② The roots separated angle of maxillary molars is different with that of the same tooth of mandibular molars. ③ It is important in tooth extraction.
出处
《牙体牙髓牙周病学杂志》
CAS
2002年第1期31-33,共3页
Chinese Journal of Conservative Dentistry
