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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。
OBJECTIVE: To establish a finite element model of 3-unit all-ceramic bridges with different thickness porcelain and base porcelain double-layer structure, in order to explore and analyze the influence of the thickness of porcelain and base porcelain on the different parts of the porcelain bridge and the interface Residual stress distribution and size provide the basis. Methods: Standard abutments were prepared according to the all-ceramic crown abutment standard on the standard dentition model with maxillary first molar missing. Three-dimensional optical scanning of the abutment standard model was performed by using WIELAND ZENOTEC Scan and the standard was formed by WIELAND ZENOTEC Cad All-ceramic crown model of 3-unit all-ceramic bridge model and 3 base models of different thickness were designed. In geomagic, they were transformed into NURBS surfaces. CATIA was used to establish 3 sets of all- Bridge solid model. Results: The residual stress mainly concentrated on the interface between the porcelain and the base porcelain. Among them, the residual stress at the coronal margin, the cusp area and the connecter was more concentrated, and the residual stress was more uniform in the thick porcelain. Conclusion: The double-layer all-ceramic bridge model established by 3D scanning is simple and accurate. The three-dimensional finite element model of all-ceramic bridge has a good structural similarity. The maximum residual stress distribution in the model is similar to that of the clinical prosthesis, which provides a model basis for fatigue life analysis of all-ceramic bridges .