应用三维有限元法分析不同基牙材料对上颌中切牙铸造陶瓷全冠碎裂的影响

目的研究三种类型和强度的基牙材料与铸造陶瓷全冠破折碎裂之间的关系。方法应用计算机建立上前牙的三维有限元模型．模拟牙本质、牙髓腔、核桩、陶瓷层等结构。分析在天然齿基牙、Co-Cr合金基牙及复合树脂基牙情况下，铸造陶瓷全冠瓷层内部及残余牙本质的应力分布情况。结果高弹性模量的Co-Cr合金核桩能够降低瓷层及残余牙本质内的应力峰值，防止瓷层破折碎裂；而弹性模量与牙本质相近的复合树脂核桩降低应力峰值的作用不明显。结论对于以活髓牙为基牙的全冠修复，应尽量保存牙髓活力后进行修复；对于行根管治疗术后的无髓牙，进行核桩修复时，宜采用高弹性模量的高熔合金，尽量避免使用弹性模量较小的复合树脂核桩。

The Effect of Different Abutment Materials on the Fraction of Casting Porcelain Crown of Maxillary Central Incisor with Three-dimensional Finite Element Method

Objective To investigate the relationship among three kinds and different strengths of abutment and the fragmentation of porcelain which may assist to improve the design of the post-core crown and full crown.Methods A three-dimensional finite element model of maxillary incisor with consisting of casting porcelain crown, post-core, similar to the clinical structure, was constructed by means of Super-SAP in computer. The tensile stress distributions on the crown and residual dentin under three kinds of abutment which were a natural tooth, a Co-Cr cast core and a composite resin core were analyzed.Results Co-Cr metal post core with high elastic modules decreased the maximum principle stress and minimum principle stress on porcelain, therefore, prevented the fragmentation of porcelain.Results This design can change the pattern of stress distribution, with high stress concentrating on the border between post and dentin. The stress distribution pattern of the composite resin post core with low elastic modules is similar to that of natural tooth abutment, but has little influence on the principle stress.Conclusions For natural tooth abutment with active pulp, we should make full crown and preserve the activity of pulp. For post-core crown, we should use metal post core with high elastic modules to avoid using resin post core with low elastic modules.