Prestresses in bilayered all-ceramic restorations
Prestresses in bilayered all-ceramic restorations
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DOI：
10.1002/jbm.b.31083
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发表时间：
2008-10-01
影响因子：
3.4
通讯作者：
Kleverlaan, Cornelis J.
中科院分区：
文献类型：
--
作者：
Aboushelib, Moustafa N.;Feilzer, Albert J.;Kleverlaan, Cornelis J.
简介：所有陶瓷系统的一般趋势是使用与框架相比热膨胀系数略低的饰面陶瓷，导致热膨胀系数（+ Δ TEC）的正失配。这种TEC不匹配背后的概念是在较弱的贴面陶瓷中产生压应力，从而提高修复体的整体强度。该技术在烤瓷熔附金属修复体（PFM）中具有良好的效果。然而，将这一概念应用于全陶瓷涂层存在问题。本研究的目的是确定双层全陶瓷涂层中由于TEC不匹配而产生的应力。材料与方法：使用TEC低于氧化锆的TEC（+ Δ TEC）的两种商业饰面陶瓷; NobelRondo zirconia（TM）和Lava Ceram（TM），加上具有与氧化锆的TEC匹配的相同TEC（Δ TEC = 0）的一种实验饰面陶瓷来饰面氧化锆盘。在双轴弯曲试验装置中加载试样，其中饰面陶瓷处于拉伸状态。使用断口分析、工程数学和有限元分析（FEA）计算了由于载荷应用和TEC不匹配而产生的应力。结果如下：在这项研究中，最高的负载在失败（64 N）获得的实验贴面氧化锆和贴面陶瓷之间的热失配是最小的。对于两种商业饰面陶瓷，位于氧化锆饰面界面处的热失配幅度（42 MPa）超过了两种材料之间的粘合强度，并导致测试期间分层失效（约。50 MPa）。意义：对于全瓷氧化锆贴面，建议尽可能减少热失配。(c)2008 Wiley Periodicals，Inc.
Introduction: A general trend in all ceramic systems is to use veneering ceramics of slightly lower thermal expansion coefficients compared with that of the framework resulting in a positive mismatch in thermal expansion coefficient (+Delta TEC). The concept behind this TEC mismatch is to generate compressive stresses in the weaker veneering ceramic and thus enhance the overall strength of the restoration. This technique had excellent results with porcelain fused to metal restorations (PFM). However, there are concerns to apply this concept to all-ceramic restorations. The aim of this research was to determine the stresses in bilayered all-ceramic restorations due to the mismatch in TEC. Materials and methods: Two commercial veneering ceramics with a TEC lower than that of zirconia (+Delta TEC); NobelRondo zirconia (TM) and Lava Ceram (TM), plus one experimental veneering ceramic with an identical TEC that matches that of zirconia (Delta TEC = 0) were used to veneer zirconia discs. The specimens were loaded in biaxial flexure test setup with the veneer ceramic in tension. The stresses due to load application and TEC mismatch were calculated using fractography, engineering mathematics, and finite element analysis (FEA). Results: In this study, the highest load at failure (64 N) was obtained with the experimental veneer where the thermal mismatch between zirconia and veneering ceramic was minimal. For the two Commercial veneer ceramics the magnitude of the thermal mismatch localized at the zirconia veneer interface (42 MPa) exceeded the bond strength between the two materials and resulted in delamination failure during testing (ca. 50 MPa). Significance: For all-ceramic zirconia veneered restorations it is recommended to minimize the thermal mismatch as much as possible. (c) 2008 Wiley Periodicals, Inc.