烤瓷熔附金属全冠受载无限元法应力分析

Study of stress to porcelain-fused-to-metal restoration by infinite element method

目的 :应用无限元方法研究临床烤瓷熔附金属全冠加载后不同组织和材料及其界面的应力分布状况 ,揭示修复体发生金 瓷结合破坏的原因 ,指导临床金 瓷修复体的设计与制作 .方法 :在二维前牙烤瓷熔附金属全冠有限元法应力分析基础上 ,将修复体唇侧颈缘出现应力集中区域选定为无限元区域进行计算 ,有限元与无限元区域的衔接采用区域分解法的D N迭代法实现 .结果 :金 瓷混合颈缘型前牙烤瓷冠加载后基牙、金属基底、遮色瓷和体瓷内大部分区域受力较均匀 ;模型唇侧颈缘处出现应力集中 ,应力集中区域内不同界面应力分布不同 ,其中沿金 瓷界面应力变化最激烈 ;随着载荷方向与牙齿长轴角度的增加 ,金 瓷界面应力水平与应力集中趋势也增加 .结论 :金 瓷混合颈缘型前牙烤瓷冠临床受力效果较为理想 ;唇侧颈缘处的应力集中是造成修复体易出现瓷崩。

AIM: To calculate the stress distribution in metal ceramic system using finite and infinite element method and to find the main factors that affect the bonding strength of metal ceramic systems in making porcelain fused to metal restoration in clinic work. METHODS: After analysis of the two dimensional porcelain fused to metal model with finite element method, labial cervical margin of the model was selected as infinite domains to calculate. D N interactive method was used to connect the finite and infinite domains. RESULTS: Stress concentrated at labial cervical margin of porcelain fused to metal restoration model, the area where porcelain fractured in the porcelain fused to metal restoration. The stress distribution at the other sections of the model was smooth and the stress magnitudes along the metal ceramic interface enhanced with the angle of loading force and axle of central incisor growing. CONCLUSION : The model with unity of porcelain to metal at the labiocervical margin is suitable for front teeth or premolars restoration. The stress concentration along the interface of metal ceramic is the most important factor in the bond failure.