动态载荷下下前牙固定桥基牙牙周膜的三维有限元法分析

目的用三维有限元法分析动态载荷下下前牙固定桥修复前、后基牙牙周膜的应力和应变分布规律。方法对有限元模型进行动态垂直、斜向加载，计算基牙牙周膜的应力和应变值，绘出牙周膜的应力分布图及牙周膜的应力- 时间曲线。结果动态载荷下，下前牙固定桥修复前、后基牙牙周膜的应力和应变分布趋势与静态载荷基本相同，但其大小明显降低，变化率为60%～75%。牙周膜的应力分布及大小具有时间依赖性，一个咀嚼周期结束后，牙周膜有残余应力存在。斜向冲击载荷时，牙周膜应力下降直至消失的时间比垂直向冲击载荷短。结论动态载荷下，下前牙固定桥修复前、后基牙牙周膜的应力和应变值明显降低。在一个咀嚼周期中，牙周膜的应力分布和大小具有时间依赖性，一个咀嚼周期结束时，牙周膜有残余应力存在。残余应力的大小与加载量及加载方向有关。加载方向是影响牙周膜应力分布、应力累积和应力释放的重要因素。

Three-dimensional stress analysis of periodontal ligament of mandible incisors fixed bridge abutments under dynamic loads by finite element method

Objective Three-dimensional finite method was used to analyze stress and strain distributions of periodontal ligament of abutments under dynamic loads.Methods Finite element analysis was performed on the model under dynamic loads with vertical and oblique directions.The stress and strain distributions and stress-time curves were analyzed to study the biomechanical behavior of periodontal ligament of abutments.Results The stress and strain distributions of periodontal ligament under dynamic load were same with the static load.But the maximum stress and strain decreased apparently.The rate of change was between 60%-75%.The periodontal ligament had time-dependent mechanical behaviors.Some level of residual stress in periodontal ligament was left after one mastication period.The stress-free time under oblique load was shorter than that of vertical load.Conclusion The maximum stress and strain decrease apparently under dynamic loads.The periodontal ligament has time-dependent mechanical behaviors during one mastication.There is some level of residual stress left after one mastication period.The level of residual stress is related to the magnitude and the direction of loads.The direction of applied loads is one important factor that affected the stress distribution and accumulation and release of abutment periodontal ligament.