Proos Kaarel A, Swain Michael V, Ironside Jim, Steven Grant P
School of Aerospace, Mechanical and Mechatronic Engineering and Faculty of Dentistry, University of Sydney, Biomaterials Science Research Unit, National Innovation Centre, Eveleigh, New South Wales, Australia.
Int J Prosthodont. 2003 Jan-Feb;16(1):82-90.
The purpose of this study was to examine the influence of the elastic modulus of cement and luting thickness on the resulting stresses in an axially loaded crown cemented onto a first premolar. A comparison of these stresses was also made with the strength of the constituent materials making up the crown.
Examination of the stresses on a restored crown was conducted using finite element analysis. Eight different axisymmetric models containing combinations of In-Ceram or gold coping, using adhesive resin or zinc phosphate cement as the luting agent, with thicknesses of either 0.05 or 0.1 mm were analyzed.
The peak tensile principal stresses in the porcelain remained below its material fracture strength. The same was true for the peak stress in the adhesive resin compared to its fracture and chemical bond strength. This was not the case for zinc phosphate. The influence of the luting agent's elastic modulus on the stresses in the crown was minor, and the influence of luting thickness was even less.
The role of the luting agent was primarily one that effectively transferred the resulting stresses between the relatively stiff coping and underlying dentin. There was no evidence of the luting agent itself playing a significant role in resisting deflection from the applied force.
本研究的目的是检验粘固剂的弹性模量和粘固厚度对轴向加载于第一前磨牙上的全冠所产生应力的影响。还将这些应力与构成全冠的材料强度进行了比较。
使用有限元分析对修复后的全冠应力进行检测。分析了八个不同的轴对称模型，这些模型包含In-Ceram或金冠核的组合，使用粘结树脂或磷酸锌粘固剂作为粘固剂，厚度分别为0.05或0.1毫米。
瓷中的峰值拉伸主应力保持在其材料断裂强度以下。与粘结树脂的断裂强度和化学键强度相比，粘结树脂中的峰值应力也是如此。磷酸锌的情况并非如此。粘固剂的弹性模量对全冠内应力的影响较小，而粘固厚度的影响更小。
粘固剂的作用主要是有效地在相对较硬的冠核和下方牙本质之间传递所产生的应力。没有证据表明粘固剂本身在抵抗外力引起的挠曲方面发挥重要作用。
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