不同移动方式下隐形矫治器的三维有限元分析

Three-Dimensional Finite Element Analysis on Invisible Dental Appliance under Different Moving Modes

目的 采用有限元方法分析不同弹性模量、厚度、牙齿移动方式对隐形矫治器变形的影响,为正畸医生制定矫治方案提供理论依据。方法 建立4种厚度、3种弹性模量共12种隐形矫治器有限元模型。对12种模型施加倾斜移动的位移载荷,分析矫治器最大Von Mises应力和变形量;对最适模型分别施加倾斜、平行以及压低移动的位移载荷,分析矫治器变形情况。结果 最大Von Mises应力随弹性模量、隐形矫治器厚度的增加而增大,变形量随矫治器厚度增加而减小;倾斜和平行移动时,隐形矫治器均在拟移动牙齿对应部位有最大的变形,拟不动牙齿对应部位有的向唇侧外凸变形,有的向舌侧内凹变形;压低移动时,矫治器严重向牙冠顶端偏移。结论 隐形矫治器最适厚度为0. 75 mm,临床上目前使用弹性模量816. 31 MPa隐形矫治器是合适的;在数字模型上将向唇侧外凸部位对应的牙齿舌侧面和向舌侧内凹对应的牙齿唇侧面增厚,用增厚后的数字模型制作隐形矫治器,优化矫治器。

Objective To analyze effects of different elastic modulus,thickness and tooth movement on deformation of the invisible dental appliance by finite element method,so as to provide theoretical references for orthodontic doctor to formulate the orthodontic treatment scheme.Methods A total of 12 finite element models of invisible appliances were established with 4 kinds of thickness and 3 kinds of elastic modulus.The displacement load of the tilting movement was applied to the 12 models,and the maximum Von Mises stress and deformation of the appliance were analyzed;the deformation of the appliance was analyzed by applying the displacement load of inclined,parallel and intrusion to the optimal model.Results The maximum Von Mises stress increased with the elastic modulus and thickness of the invisible appliance increasing.The deformation decreased with the appliance thickness increasing.When the tooth was under inclined and parallel movement,the maximum deformation was found in the corresponding part of the tooth.Some of the corresponding parts of the immovable teeth were deformed to the lip convex side and some to the tongue side with internal concave deformation,and the appliance deviated seriously to top of the crown when the tooth was under intrusion movement.Conclusions The optimum thickness of invisible dental appliance was 0.75 mm,and the elastic modulus 816.31 MPa that currently used in clinic was suitable.In the digital model,the tongue side of the teeth corresponding to the labial protruding part and the lip side of the tooth corresponding to the concave side of the tongue side can be thickened,and the invisible appliance can be optimized by using the thickened digital model.