Post-Graduate Program in Dental Science, Federal University of Santa Maria (UFSM), 1184 Floriano Peixoto, 7th floor, 97015-372, Santa Maria, RS, Brazil.
Department of Biomaterials and Biomimetics, New York University, 433 First Avenue, 8th floor, 10010, New York, NY, USA.
Dent Mater. 2019 May;35(5):807-817. doi: 10.1016/j.dental.2019.02.016. Epub 2019 Mar 4.
A systematic review of in vitro studies was conducted to assess the effect of thermal treatments on flexural strength or critical load to failure of porcelain-veneered zirconia (PVZ).
Literature searches were performed up to June 2018 in PubMed/MEDLINE, Scopus and Web of Science databases, with no publication year or language limits.
From 393 relevant studies, 21 were selected for full-text analysis, from which 7 failed to meet the inclusion criteria. The 14 remaining papers were included in the systematic review: 8 for meta-analysis and 6 restricted to descriptive analyses. Hand searching of reference lists resulted in no additional papers.
In vitro studies using PVZ specimens testing the influence of thermal treatments on the fracture resistance to monotonic or cyclic loading. Papers evaluating cooling rate were divided into those applying fast cooling from above the porcelain glass transition temperature (T), or from below it. Meta-analyses were performed separately for flexural strength and critical load to failure, using random effects at a 5% significance level.
Delaying furnace opening at a temperature below the porcelain T is advised for PVZ restorations, in order to improve their fracture resistance. Additional information is required to confirm the apparent beneficial effect of self-glaze and repeated veneer firings on the mechanical properties of these restorations. Finally, in order to obtain conclusive and relevant evidence regarding thermal treatments and the fracture resistance of PVZs, future studies should concentrate on anatomically-correct crown specimens.
对评估热疗处理对烤瓷氧化锆（PVZ）弯曲强度或临界失效负荷的体外研究进行系统评价。
截至 2018 年 6 月，在 PubMed/MEDLINE、Scopus 和 Web of Science 数据库中进行了文献检索，未设置出版年份或语言限制。
从 393 篇相关研究中，选择 21 篇进行全文分析，其中 7 篇不符合纳入标准。其余 14 篇论文纳入系统评价：8 篇用于荟萃分析，6 篇仅限于描述性分析。通过手动搜索参考文献，没有发现其他论文。
使用 PVZ 标本进行的体外研究，测试热疗处理对单调或循环载荷下断裂阻力的影响。评估冷却速率的论文分为在高于或低于瓷化玻璃转化温度（T）的温度下快速冷却的论文。使用随机效应，在 5%的显著性水平下，分别对弯曲强度和临界失效负荷进行荟萃分析。
建议在低于瓷化 T 的温度下延迟炉门打开，以提高 PVZ 修复体的断裂阻力。需要进一步的信息来确认自釉和重复贴面烧制对这些修复体机械性能的明显有益效果。最后，为了获得关于热疗处理和 PVZ 断裂阻力的明确和相关证据，未来的研究应集中在解剖学上正确的冠标本上。
