Dental Prosthetics Technology, Vocational School of Health Services, Hacettepe University, Ankara, Türkiye.
Department of Prosthodontics, Faculty of Dentistry, Istanbul Okan University, Istanbul, Türkiye.
Biomed Tech (Berl). 2023 Mar 20;68(4):437-443. doi: 10.1515/bmt-2022-0338. Print 2023 Aug 28.
The strength of zirconia ceramic materials used in restorations is dependent upon sintering. Varying sintering protocols may affect the biaxial flexural strength of zirconia materials. This in vitro study was conducted to investigate the effects of sintering parameters on the biaxial flexural strength of monolithic zirconia. Two different monoblock zirconia ceramics were used. Following coloration, samples of both types of ceramics were divided into groups according to whether or not biaxial flexural strength testing was performed directly after sintering or following thermocycling. Biaxial flexural strength data was analysed with a Shapiro Wilk normality test, followed by 1-way ANOVA, Tukey post hoc tests for inter-group comparisons, and paired samples t-tests for intra-group comparisons. A significant difference was found between the biaxial flexural strengths of Zircon X and Upcera ceramics before thermocycling (p<0.05). In both Zircon X and Upcera ceramic groups, the thermocycling process created a significant difference in the biaxial flexural strength values of the ceramic samples in Group 6 (p<0.05) which had the slowest heating rate and longest holding time. The zirconia ceramics have higher BFS at higher heating rates either before or after thermocycling. The holding time has significant effects on thermocycling and flexural strength. The zirconia achieved its optimum strength when it sintered at longer time regardless of heating rates.
用于修复的氧化锆陶瓷材料的强度取决于烧结。不同的烧结方案可能会影响氧化锆材料的双轴弯曲强度。本体外研究旨在探讨烧结参数对整体氧化锆双轴弯曲强度的影响。使用了两种不同的整体氧化锆陶瓷。着色后，根据是否在烧结后直接进行双轴弯曲强度测试或在热循环后进行，将两种类型的陶瓷样品分为两组。使用 Shapiro Wilk 正态性检验对双轴弯曲强度数据进行分析，然后进行单向方差分析、Tukey 事后检验进行组间比较，以及配对样本 t 检验进行组内比较。在热循环之前，Zircon X 和 Upcera 陶瓷的双轴弯曲强度之间存在显著差异（p<0.05）。在 Zircon X 和 Upcera 陶瓷组中，热循环过程导致第 6 组陶瓷样品的双轴弯曲强度值发生显著差异（p<0.05），第 6 组的加热速率最慢，保持时间最长。在热循环前后，加热速率较高的氧化锆陶瓷具有更高的 BFS。保持时间对热循环和弯曲强度有显著影响。无论加热速率如何，氧化锆在较长时间烧结时都能达到最佳强度。
