推杆式矫治器前导下颌三维有限元模型的初步构建与分析

目的 构建推杆式矫治器(Forsus)前导下颌的三维有限元模型,分析下颌短期前导后的应力和位移,以期为临床应用和改良推杆式矫治器提供参考.方法 选择1例处于生长发育高峰期的Ⅱ类错(牙合)下颌后缩患者,用MBT直丝弓矫治器排齐整平上下牙列达安装推杆式矫治器要求后,经螺旋CT扫描,用Mimics 9.0、Abaqus 6.5软件构建推杆式矫治器前导下颌的三维有限元模型(设计时考虑颌骨的黏弹性和黏塑件),分析前导1、15、300 S后下颌的应力和位移.结果 获得包含MBT直丝弓矫治器的推杆式矫治器前导下颌的三维有限元模型,前导下颌15和300 s后应力集中区均位于髁突前缘、下颌切迹及下颌磨牙区,最大应力值分别为34.47 MPa和34.45 MPa;前导下颌1、15、300 S后最大位移区均出现于下切牙和颏部,最大位移量随加载时间延长而增加,由3.30×10-2mm增至1.15 mm;最大位移区沿下颌骨体向后扩大,髁突位移量由加载1 s时的1.65×10-2 mm减少至加载300 s时的3.27×10-5mm.结论 本项研究在考虑颌骨黏弹性和黏塑性的情况下初步构建推杆式矫治器前导下颌的三维有限元模型.研究结果提示,推杆式矫治器加载一定时间后下颌的应力分布趋于稳定,推杆式矫治器具有促进下颌体整体向前向下改建的作用.

Three-dimensional finite element analysis of stress distribuffon in mandible advanced with Forsus

Objective To construct a three-dimensional finite element model of mandible and to analyze the stress distribution in mandible advaneed with Forsus.Methods One growing patient with mandibular retrusion was selected.After leveling and aligning with MBT(Mclanghlin BenneR Treriri)straight-wire appliance to achieve the request of forsus with the spiral CT,a three-dimensional finite element model was constructed and the stress distilbution in mandible after advancing at 1 second.15 seconds and 300 seconds wag analyzed.Results The three-dimensional finite element model included MBT stralght-wire appliance.The stress concentration areas were located in the front side of the condylar process.the sigmoid notch and mandibular molar areas at 15 seconds and 300 seconds after mandibular advancement.The maximum stress value8 were 34.47 MPa and 34.45 MPa.repectively.With the extension of loading time,the largest displacement increased from 3.30×10-2 mm to 1.15 mm and the regiOil of the largest displacement extended backwards along the bodv of mandible.However.the displacement of condyle reduced from 1.65×10-2mm at 1 second to 3.27×10-5 mm at 300 seconds after mandibular advancement.Conclusions The three-dimensional finite element model considered the viscoelasticity and viscoplasticity of mandibular.The result suggested that the stress distribution in the mandible gradually became stable after the application of Forfus and the appliance caused downward and forward mandibular modification.