根管锥度和根管固位材料对牙体组织应力分布影响的三维有限元分析

Three-dimensional finite element analysis of effect of root canal taper and post on tooth stress distribution

目的 观察3种锥度根管采用不同根管桩修复对牙体组织应力分布的影响,以期为临床合理选用根管桩提供实验依据.方法 分别建立35号K锉、ProTaper和Profile器械根管预备后的下颌第一磨牙三维有限元模型,并分别模拟纤维树脂桩、不锈钢根管桩和银汞合金桩根管固位修复.运用Marc有限元软件,采用中央垂直加载,分析3种不同根管桩修复时牙颈部和牙根部应力分布的状况.结果 不同根管锥度对3种根管固位方式下的应力分布趋势无明显影响.不锈钢根管桩应力集中部位主要位于远中牙根中上部,远中根管口最高Von-Mises应力约为45 Mpa;银汞桩应力集中部分主要位于远中根管口上端及髓腔内,远中根管口最高Von-Mises应力约为16 Mpa;纤维树脂桩应力分布较均匀,未见明显应力集中.结论 纤维桩是比较理想的根管固位形式,应力分布接近于无根管桩状态;不锈钢根管桩在根中部容易形成高应力集中,增加根折发生率.

Objective To evaluate the effect of root canal taper and post on tooth stress distribution. Methods Three-dimensional finite element models of human mandibular first molar with root canals prepared with 35# K file, ProTaper and Profile were established. The tooth were restored with fiberresin, stainless steel and silver amalgam posts respectively. A vertical load on tooth occlusal surface was simulated. Marc software was used to analyze and calculate the stress distributions in the tooth restored with three kinds of different root canal posts, especially the in the cervical part and root. Results Different tapered root canals had no obvious influence on stress distribution in all three different posts. Stress distribution of stainless steel post located at the cervical and middle part of distal root, the highest Von-Mises stress was about 45 MPa. Stress distribution of silver amalgam post located at the orifice of root canal and pulp fundus, the highest Von-Mises stress was about 16 MPa. Stress distribution of fiber-resin post had no obvious stress concentration. Conclusions Fiber-resin post is the most ideal root canal post. Stainless steel post causes remarkable stress concentration in the root, which may raise the possibility of root fracture.