Residual stresses in porcelain-veneered zirconia prostheses
Residual stresses in porcelain-veneered zirconia prostheses
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DOI：
10.1016/j.dental.2012.04.019
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发表时间：
2012-08-01
期刊：
影响因子：
5
通讯作者：
Zhang, Yu
中科院分区：
文献类型：
--
作者：
Baldassarri, Marta;Stappert, Christian F. J.;Zhang, Yu
目标。在氧化锆-陶瓷假体的覆盖瓷中有意地引入压应力以防止单板断裂。然而，最近的理论分析预测，陶瓷中的残余应力也可能是拉伸的。本研究的目的是确定具有解剖氧化锆顶部设计的全轮廓固定义齿（FDPs）瓷贴面中残余应力的类型和大小，并使用完善的维氏压痕法去除氧化锆的对照瓷。生产了6个3单元氧化锆fdp （NobelBiocare, Gothenburg, Sweden）。瓷器是用缓慢的冷却速度手工贴面的。每个FDP平行于咬合平面进行维氏压痕切片（n = 143，载荷= 9.8 n，停留时间= 5 s）。分别在烤瓷-氧化锆贴面试件（双层，n = 4）和不带氧化锆核的烤瓷试件（单层，n = 2）中进行试验。在横向和径向（即平行和垂直于单板/芯界面）上，双层的平均裂纹长度和标准差分别为67 +/- 12 μ m和52 +/- 8 μ m，单层的平均裂纹长度和标准差分别为64 +/- 8 μ m和64 +/- 7 μ m。这些结果表明，在瓷贴面的主体中，主要的环向压应力（类似于40-50 MPa）和中等的径向拉应力（类似于10 MPa）。维氏压痕是测定单板氧化锆体系残余应力的一种有效方法。我们的研究结果揭示了覆盖瓷的径向拉伸应力的存在，这可能是在这些假体中观察到的大面积临床片状骨折的原因。(C) 2012年牙科材料学会。Elsevier Ltd.出版。版权所有。
Objectives. Compressive stress has been intentionally introduced into the overlay porcelain of zirconia-ceramic prostheses to prevent veneer fracture. However, recent theoretical analysis has predicted that the residual stresses in the porcelain may be also tensile in nature. This study aims to determine the type and magnitude of the residual stresses in the porcelain veneers of full-contour fixed-dental prostheses (FDPs) with an anatomic zirconia coping design and in control porcelain with the zirconia removed using a well-established Vickers indentation method.Methods. Six 3-unit zirconia FDPs were manufactured (NobelBiocare, Gothenburg, Sweden). Porcelain was hand-veneered using a slow cooling rate. Each FDP was sectioned parallel to the occlusal plane for Vickers indentations (n = 143; load = 9.8 N; dwell time = 5 s). Tests were performed in the veneer of porcelain-zirconia specimens (bilayers, n = 4) and porcelain specimens without zirconia cores (monolayers, n = 2).Results. The average crack lengths and standard deviation, in the transverse and radial directions (i.e. parallel and perpendicular to the veneer/core interface, respectively), were 67 +/- 12 mu m and 52 +/- 8 mu m for the bilayers and 64 +/- 8 mu m and 64 +/- 7 mu m for the monolayers. These results indicated a major hoop compressive stress (similar to 40-50 MPa) and a moderate radial tensile stress (similar to 10 MPa) in the bulk of the porcelain veneer.Significance. Vickers indentation is a powerful method to determine the residual stresses in veneered zirconia systems. Our findings revealed the presence of a radial tensile stress in the overlay porcelain, which may contribute to the large clinical chip fractures observed in these prostheses. (C) 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.