Most of which happened in mesiobuccal canal of maxillarymolar and mesial canal of mandibular molar, accounting for 70.7%.
器械折断于上磨牙近颊根管和下磨牙近中根管者居多，占70.7%。器械折断在根管中下段多见，占70%。
2
Result: the three-dimensional models of the first maxillarymolar residual root restored with post-core crown were generated.
结果：建立了上颌第一磨牙残根桩核冠的三维有限元模型。
3
Objective: To evaluate the clinical applications and therapeutic effect of maxillary sinus floor lifting and dental implantation in the patients of maxillarymolar missing.