下颌第一磨牙任意两壁缺损不同充填材料全瓷冠修复的三维有限元应力分析

Three-dimensional finite element analysis on half of the structure defect with different filling materials and all-ceramic crown restoration of mandibular first molar

目的:应用三维有限元法对不同充填材料全瓷冠修复两壁缺损下颌第一磨牙应力分析。方法:通过CBCT扫描离体牙,Mincis三维重建,Geomagic优化处理,Ansys布尔运算建立下颌第一磨牙两壁缺损6种模型,分别使用银汞合金充填及复合树脂充填全瓷冠修复,在最大、垂直、斜向及水平4种载荷下,分别比较牙本质Mohr应力分布及牙本质最大Mohr值。结果:下颌第一磨牙牙冠缺损1/2时,不同充填材料全瓷冠修复,同一载荷下6种缺损模型的牙根应力分布无明显区别,银汞合金充填全瓷冠修复的应力集中区较复合树脂充填全瓷冠修复更偏向根方。结论:下颌第一磨牙牙冠缺损1/2时,复合树脂充填全瓷冠修复优于银汞合金充填全瓷冠修复,且缺损位置对修复效果无明显影响。

Objective：To make a mechanical analysis on 3-dimensional finite element models of the mandibular first molar with half of the structure defect,which were restored by different filling materials and all-ceramic crown,and to provide a guideline for planning restoration for such kind of tooth structure defect. Method：3D finite element models of the restored first mandibular molars were constructed by CT image reconstruction technique. Then MIMICS software was used to separate the areas and finish 3D calculation. GEOMAGIC software was also applied to modify and generate a NURBS surface in each patch. All components of the models were assembled under the ANSYS preprocessor. The Mohr strength theory was applied for comparing the maximum Mohr stress value of dentin and stress concentration areas in six models under the maximum,vertical,inclined and horizontal direct loads. Result：The restoration effects in six models were compared,the maximum Mohr stress value of dentin and stress concentration areas were not obviously difference.The stress area in the model with amalgam filling and all-ceramic crown restoration was generally closer to the root tip than that in the model with composite resin filling and all-ceramic crown restoration. Conclusion：The location of residual dentin has little influence on the stress value and distribution,when restored by all-ceramic crown. The composite resin filling and the all-ceramic crown restoration are relatively better than amalgam filling and all-ceramic crown restoration.