Motta Andréa Barreira, Pereira Luiz Carlos, da Cunha Andréia R C C, Duda Fernando Pereira
Department of Metallurgy and Materials Engineering and Prosthesis and Dental Materials Department, Federal University of Rio de Janeiro, PEMM/COPPE/UFRJ, Rio de Janeiro, Brazil.
Artif Organs. 2008 Apr;32(4):283-91. doi: 10.1111/j.1525-1594.2008.00544.x.
Studies pertaining to the mechanical behavior of fixed partial dentures (FPDs) frequently found the highest tensile stress values at the connector region when load is applied at the pontic central region. The connector region is considered the weakest point of the prosthesis with the greatest potential of fractures, regardless of the material used. This 2D finite element study compared the stress distribution on three-element all-ceramic and metal-ceramic FPDs with different loading conditions. Three FPD models were designed: (i) metal-ceramic FPD; (ii) all-ceramic FPD with the veneering porcelain only on the occlusal face; and (iii) all-ceramic FPD with the veneering porcelain on the occlusal and cervical face of the pontic. Loads of 100 N were applied following these simulations: (i) distributed on all working cusps; (ii) only on the abutment teeth; and (iii) only on the pontic. There is a significant change on the stress distribution and on the tensile stress values when the load configuration is changed. The stress distribution from the load applied on the abutments was significantly better compared with the other two load simulations. When the loads were applied on the pontic and distributed on all working cusps, the highest tensile stress values appeared on the cervical region of the connectors between the abutments and the pontic. However, when the load was applied on the abutment teeth, the maximum tensile stress value significantly decreased and was located on the occlusal region of the connectors. In fact, the load applied on the pontic region does not simulate the clinical situation. Studies using this load configuration have overestimated the connector regions as having the highest probability of failures.
关于固定局部义齿(FPD)力学行为的研究经常发现,当在桥体中央区域施加负载时,连接体区域的拉应力值最高。无论使用何种材料,连接体区域都被认为是修复体中最薄弱的点,具有最大的骨折可能性。这项二维有限元研究比较了不同加载条件下三元全瓷和金属烤瓷FPD的应力分布。设计了三种FPD模型:(i)金属烤瓷FPD;(ii)仅在咬合面有饰面瓷的全瓷FPD;(iii)桥体的咬合面和颈面都有饰面瓷的全瓷FPD。在以下模拟后施加100 N的负载:(i)分布在所有工作尖上;(ii)仅在基牙上;(iii)仅在桥体上。当负载配置改变时,应力分布和拉应力值会有显著变化。与其他两种负载模拟相比,施加在基牙上的负载产生的应力分布明显更好。当负载施加在桥体上并分布在所有工作尖上时,最高拉应力值出现在基牙与桥体之间连接体的颈部区域。然而,当负载施加在基牙上时,最大拉应力值显著降低,并位于连接体的咬合区域。事实上,施加在桥体区域的负载并不能模拟临床情况。使用这种负载配置的研究高估了连接体区域出现故障的可能性。