A Photoelastic Assessment of Residual Stresses in Zirconia-Veneer Crowns
A Photoelastic Assessment of Residual Stresses in Zirconia-Veneer Crowns
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DOI：
10.1177/0022034511435100
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发表时间：
2012-03-01
影响因子：
7.6
通讯作者：
Lohbauer, U.
中科院分区：
文献类型：
--
作者：
Belli, R.;Monteiro, S., Jr.;Lohbauer, U.
在氧化锆假体的临床试验中，观察到贴面内的残余应力与贴面碎裂的高发生率有关。我们假设氧化锆基础结构和贴面瓷之间的热失配，以及用于冷却氧化锆贴面冠的速率，将与贴面层内建立的残余应力的大小成正比。两种具有不同热膨胀系数的瓷被用来贴面氧化锆顶盖，以产生高或低的热失配。根据快速或缓慢冷却方案冷却冠。根据光弹性原理，在1.0 mm厚的牙冠切片中，利用偏振光波的延迟来计算单板上的残余应力大小和分布。而热失配是影响单板最大应力发展的重要因素，冷却速率的作用较小。弯曲表面的应力集中的优先网站，无论热失配或冷却速率。
Residual stresses within the veneer are linked to the high prevalence of veneer chipping observed in clinical trials of zirconia prostheses. We hypothesized that the thermal mismatch between the zirconia infrastructure and the veneer porcelain, as well as the rate used for cooling zirconia-veneer crowns, would be directly proportional to the magnitude of residual stresses built within the veneer layer. Two porcelains with different coefficients of thermal expansion were used to veneer zirconia copings, to create high or low thermal mismatches. The crowns were cooled according to a fast- or a slow-cooling protocol. The retardation of polarized light waves was used to calculate the residual stress magnitude and distribution across the veneer, according to the photoelasticity principle, in 1.0-mm-thick crown sections. While thermal mismatch was an important factor influencing the maximum stress development in the veneer, cooling rate had a minor role. Curved surfaces were preferential sites for stress concentration regardless of thermal mismatch or cooling rate.