目的:探讨固定桥双基牙侧牙槽骨有不同程度水平吸收时,基牙牙周膜的等效应力值和分布的变化,以指导临床固定桥的合理设计。方法:采用螺旋CT扫描技术与MIMICS、AnSyS软件相结合建立双基牙侧牙槽骨有不同程度水平吸收后的三基牙双端固定桥的三维有限元模型,施加垂直和斜向45°载荷,分析双基牙侧牙周膜的应力分布状况。结果:1斜向载荷下各模型应力值均大于垂直向载荷时的应力,应力集中现象也较垂直向载荷时明显;2在垂直或倾斜载荷下,有牙槽骨吸收的第二前磨牙侧增加牙周组织健康的第一前磨牙时,应力均变大以分担牙合力;若增加的第一前磨牙有不同程度的牙槽骨吸收,垂直载荷时应力值变化不大,斜向载荷时应力值减小,但应力集中现象较无吸收时明显。结论:增加牙槽骨有不同程度吸收的基牙不能有效地发挥分散牙合力的作用,不适合做固定桥基牙。加载方向是影响应力分布的重要因素,应注意防止产生过大的侧向力。AIM: To investigate the stress distribution of abutment tooth periodontal ligament when there are different levels of alveolar bone resorption at the abutment teeth with rigid fixed bridge design.METHODS: A three dimensional finite element model with different levels of alveolar horizontal absorption at the abutment teeth was established by CT scanning using Mimics 8.1 and Ansys 11.0.Vertical and oblique loading was added to test stress the distribution at the abutment teeth.RESULTS: When the periodontally healthy first premolar was added as additional abutment tooth,vertical loading and oblique loading could result in more evenly distributed stress.However,when alveolar bone resorption existed in first premolar,little stress distribution change was observed at vertical loading.But oblique loading led to more concentrated stress.CONCLUSION: Adding an abutment tooth with alveolar bone resorption can not improve stress distribution,hence it is not suitable for rigid fixed bridge.The direction of loading seems to play a significant role in determining stress distribution.The oblique force on the bridge should be avoided or reduced as possible.厦门市科技局资助课题(3502Z20094013
