不同弹性模量的热压膜材料远移上颌磨牙的有限元分析

Distalization of maxillary molars by hot pressed membrane materials with different elastic modulus:A finite element analysis

目的:计算不同弹性模量的透明矫治器推上颌磨牙远移时的应力大小、位移趋势及瞬时应力。方法:建立弹性模量为400 MPa(A组)、600 MPa(B组)、800 MPa(C组)、1000 MPa(D组)、1200 MPa(E组)的5种透明矫治器、上颌第二磨牙都远移0.25 mm的有限元模型,比较各组磨牙位移差异。结果:本实验中,E组第二磨牙位移量最大,A组最小,各组第二磨牙移动方式均为倾斜形式,其支点位于根中1/3与根尖1/3交界处;A组透明矫治器位移量最大,E组最小;牙周膜最大应力E组高于A组。结论:透明矫治器在推磨牙向后时,第二磨牙移动方式均为远中倾斜移动,透明矫治器的弹性模量越大,第二磨牙的位移量越大且牙周膜的瞬时应力也增大。

Objective:To measure the amount of the stress and displacement of upper molar using an invisible orthodontic appliance with different elastic modulus.Methods:5 types of invisible orthodontic appliance models with different elastic modulus of 400 MPa(group A),600 MPa(group B),800 MPa(group C),1000 MPa(group D)and 1200 MPa(group E)were respectively established;the upper second molars were designed to move distally for 0.25 mm in finite element model.The tooth displacement was compared among the groups.Results:In this experiment,the most molar displacement was observed in group E,and the lowest in group A.The movement of the second molars in each group was oblique,and the fulcrum was located at the junction of the middle 1/3 and the apical 1/3 of the root.The displacement of the invisible orthodontic appliance in group A was the highest and in group E was the lowest;the maximum stress of periodontal ligament was higher in group E than that in group A.Conclusion:When the invisible orthodontic appliance moves the second molar distally,the second molar will move distally in an oblique direction.The greater elastic modulus of the invisible orthodontic appliance may produce the greater displacement of the second molar with a maximum stress of periodontal ligament.