不同厚度饰瓷与基底瓷双层结构全瓷桥三维有限元模型的建立

目的:建立不同厚度饰瓷与基底瓷双层结构后牙3单位全瓷桥有限元模型,为探索分析高温烧结冷却过程中,饰瓷与基底瓷厚度对全瓷桥不同部位以及结合界面处的残余应力分布及大小提供基础。方法:在上颌第1磨牙缺失的标准牙列模型上,按照全瓷冠基牙要求对基牙进行标准预备,再使用WIELAND ZENOTEC Scan对基牙标准模型进行三维光学扫描,通过WIELAND ZENOTEC Cad形成标准设计的3单位全瓷桥模型全瓷冠模型和3组不同厚度的基底模型;在geomagic中转化成NURBS曲面;导入CATIA建立3组不同厚度饰瓷与基底瓷双层结构后牙3单位全瓷桥实体模型。结果:残余应力主要集中在饰瓷与基底瓷结合界面处,其中冠颈缘处、牙尖相对应部位及连接体处残余应力较为集中,在修饰瓷较厚的部位残余应力分布较为均匀。结论:运用三维扫描建立的双层全瓷桥模型简单且精确。实验所建双层结构后牙3单位全瓷桥三维有限元模型具有良好的结构相似性,模型最大残余应力分布与临床修复体易破坏部位相似,为全瓷桥的疲劳寿命分析提供了模型基础。

Establishment of the three-dimensional finite element model with the different thickness of porcelain and decorated and bilayered of all-ceramic bridge

Objective: To investigate the effect of different veneer thickness and core thickness on the residual stress distribution of the 3D finite element model of the bilayrerd all-ceramic bridge during the process of high-temperature sintering and cooling. Methods:The standard preparation of abutment tooth is done based on the requirement of all ceramic crown of it,which is performed on the maxillary dentition model without the first molar. The 3D surface picture was obtained through WIELAND ZENOTEC Scan. Through WIELAND ZENOTEC cad,geomagic and CATIA were employed to build and to transform 3D surface picture of different veneer thickness and core thickness of the bilayered all-ceramic bridage into the 3D solid model. Results: The residual stress of the all-ceramic bridage distributed the interface between the core and veneer on the margin. The maximum residual stress was found at the edge of the veneer and connector. The residual stress was minimum where the veneer ceramic was thickest. The residual stress also increased with the cooling temperature decreasing and with the thermal expansion and the veneer thickness increase. Conclusion: The method of building allceramic bridge is convenient and accurate. The residual stress analysis can be achieved through the establishment of bilayrerd all-ceramic bridge. And the result will be helpful to analyze fatigue life capability of the all-ceramic bridge.