三种弓丝在内收前牙时牙周组织应力分布三维有限元分析

目的:比较平直不锈钢方丝?前牙段带20°正转矩的不锈钢方丝与复合转矩弓丝在内收上颌前牙时上颌4个切牙的位移趋势和牙周组织应力分布?方法:建立包含矫治器的上颌三维有限元模型,运用三维有限元分析,分别为复合转矩弓丝和带20°正转矩的不锈钢方丝上颌四颗切牙施加相对应的方向为牙冠唇向?牙根舌向的位移载荷,并对3种弓丝整体施加1.47N的内收力,计算得到牙周膜应力分布情况?结果:在前牙内收时,使用平直不锈钢方丝时,主要表现为冠舌向的转矩运动,使用另外2种弓丝时,主要表现为冠唇向的转矩运动,使用复合转矩弓丝的牙周膜应力分布与带转矩的不锈钢丝类似,但最大主应力分布面积明显小于不锈钢丝组,其最大主应力值与带转矩不锈钢丝相比也大为减小?结论:在前牙内收阶段使用复合转矩弓丝,能保持4个前牙的正常唇倾度,前牙接近整体移动,且最大主应力值明显较带20°正转矩的不锈钢方丝小,更符合生理移动的要求?

3D definite element analysis of stree distribution in periodontal tissue using three types of archwire in retraction of upper incisors

Objective: To compare the difference of creep tendency and stress distribution in periodontal tissue by using of flat stainless steel rectangular arch,20°torque archwire and compound retraction arch wire in retraction of 4 upper incisors. Methods: A model was established by 3D finite element analysis,on which three kinds of archwire was loaded. An additional moment was added to the model with the compound retraction arch wire and 20° torque archwire. The stress distribution in periodontal tissue was calculated. Results: A crown lingual movement tendency was observed when the flat stainless steel rectangular arch was used. When the other two wires were used,a crown labial movement tendency was observed. However,the maximum stress of the compound retraction arch model was less than the 20°torque archwire. Conclusion: Compared with the other two kinds of archwire,the compound retraction archwire can decrease the injury to the periodontal tissue and achive a better therapeutic effect.