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目的:建立不同厚度饰瓷与基底瓷双层结构的后牙三单位全瓷桥有限元模型,分析饰瓷与基底瓷厚度对全瓷桥残余应力的分布及其影响。方法:使用WIELAND ZENOTEC Scan对上颌后牙三单位固定桥基牙标准模型进行三维光学扫描,在上述模型基础上通过WIELAND ZENOTEC Cad;Geomagic;CATIA构建三组不同厚度饰瓷与基底瓷双层结构后牙三单位全瓷桥实体模型,将模型导入ABAQUS6.10有限元软件,分析修复体从575℃降至室温25℃过程中残余应力的形成及分布。结果:全瓷修复体残余应力主要分布在饰瓷与基底瓷结合界面处,其中冠边缘、连接体处修饰瓷分布较薄的部位界面处残余应力较为集中,而在修饰瓷较厚的部位残余应力分布较为均匀。随着温度的降低,饰瓷与基底瓷结合界面的残余应力逐渐增大。随着饰瓷与基底瓷热膨胀系数之差逐渐增大和饰瓷厚度的增加,结合界面的残余应力也逐渐增大。结论:双层结构全瓷桥三维有限元模型的建立使得修复体残余应力分析得以实现。修饰瓷较薄和热膨胀系数差较大时残余应力分布较大,在进行全瓷桥修复时除饰瓷与基底瓷热膨胀系数匹配外,要保证饰瓷一定的厚度。
OBJECTIVE: To establish the finite element model of posterior three-unit all-ceramic bridge with different thickness porcelain and base porcelain double-layer structure, and to analyze the distribution and influence of the residual stress of all-ceramic porcelain bridge with the porcelain thickness. METHODS: Three-dimensional optical scanning was performed on the standard model of the abutment of three fixed maxillary posterior teeth using WIELAND ZENOTEC Scan. Based on the above model, three sets of double-layered structures with different thicknesses of porcelain and base porcelain were constructed by WIELAND ZENOTEC Cad; Geomagic; CATIA Tooth three unit porcelain bridge solid model, the model was imported ABAQUS6.10 finite element software, analysis of restoration from 575 ℃ to room temperature 25 ℃ in the process of residual stress formation and distribution. Results: The residual stress of the all-ceramic restoration was mainly distributed at the interface between the porcelain and the basement porcelain. The residual stress at the interface of the porcelain with the thinner distribution of the porcelain edge and the connecter was more concentrated, while the residual stress was concentrated in the thicker part of the porcelain The stress distribution is more uniform. As the temperature decreases, the residual stress of the interface between the porcelain and the base porcelain increases gradually. As the difference between the thermal expansion coefficient of the decorative porcelain and the base porcelain gradually increases and the porcelain thickness increases, the residual stress of the bonding interface also increases gradually. Conclusion: The establishment of three-dimensional finite element model of full ceramic bridge with double-layer structure enables the residual stress analysis of the restoration to be realized. When the modified porcelain is thinner and the difference of thermal expansion coefficient is larger, the residual stress distribution is larger. In addition, when the porcelain bridge is repaired, the thermal expansion coefficient of the porcelain and the base porcelain should be matched to ensure that the porcelain has a certain thickness.