不同设计形式铸造桩核修复重度缺损磨牙三维有限元分析

Three-dimensional finite element analysis of badly damaged maxillary first molar restored with cast post and cores in different forms

目的通过三维有限元方法分析不同根桩数目铸造桩核修复重度缺损上颌第一磨牙后牙体组织应力分布。方法以右上颌第一磨牙为标本,通过CT扫描获得图像信息,采用Mimics三维建模软件、FreeForm视觉设计系统建立健康上颌第一磨牙、单根铸造桩核、双根铸造桩核以及三根铸造桩核修复重度缺损上颌第一磨牙的三维有限元模型;利用Ansys有限元软件分析比较加载后牙体组织的Von Mises应力、拉应力和压应力峰值分布和变化。结果随着根桩数目从单根桩增加到双根桩和三根桩,牙本质的Von Mises应力峰值和压应力峰值呈减小趋势,而拉应力峰值增大并集中在与核有夹角的腭根桩和远中颊根桩末端对应的根管牙本质。桩核修复后的磨牙牙体组织应力峰值均比健康第一磨牙小。结论铸造桩核修复重度缺损上颌第一磨牙时,根桩数目和桩与核的夹角均影响牙体组织应力分布。

Objective The study was designed to analyze the stress distribution of badly damaged maxillary first molar restored with cast post and cores in different forms. Methods Intact human right maxillary first molars and badly damaged maxillary first molar restored with cast post and cores were used to build three-dimensional finite element models. Three-dimension finite element model were created with soft wares of Mimics, Ansys and Freeform. Three-dimension finite element analysis was performed on the models under static loads, and stress distribution among different models was evaluated. Results The maximal Von Mises stress on dentine decreased when the amounts of posts increased. The maximal tensile stress on dentine increased when the amounts of posts increased. The maximal tensile stress was located in lingual and distal lingual root canal dentine around the tip of post. Conclusions The amounts of posts and he angle between post and core influenced stress distribution of badly damaged maxillary first molar restored with cast post and core.