MDS-PhD Graduate Program in Oral Science, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil; Department of Dental Material Sciences, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, The Netherlands.
Faculty of Odontology, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
Mater Sci Eng C Mater Biol Appl. 2016 Jun;63:70-7. doi: 10.1016/j.msec.2016.02.049. Epub 2016 Feb 22.
This study aimed to investigate the effects of grinding with diamond burs and low-temperature aging on the mechanical behavior (biaxial flexural strength and structural reliability), surface topography, and phase transformation of a Y-TZP ceramic for monolithic dental restorations. Disc-shaped specimens (Zirlux FC, Ivoclar Vivadent) were manufactured according to ISO 6872 (2008) and divided in accordance with two factors: "grinding - 3 levels" and "LTD - 2 levels". Grinding was performed using a contra-angle handpiece under constant water-cooling with different grit-sizes (extra-fine and coarse diamond burs). LTD was simulated in an autoclave at 134°C, under a pressure of 2 bar, over a period of 20h. Surface topography analysis showed an increase in roughness based on surface treatment grit-size (Coarse>Xfine>Ctrl), LTD did not influence roughness values. Both grinding and LTD promoted an increase in the amount of m-phase, although different susceptibilities to degradation were observed. According to existing literature the increase of m-phase content is a direct indicative of Y-TZP degradation. Weibull analysis showed an increase in characteristic strength after grinding (Coarse=Xfine>Ctrl), while for LTD, distinct effects were observed (Ctrl<Ctrl LTD; Xfine=Xfine LTD and Coarse=Coarse LTD). Weibull moduli were statistically similar between all tested groups. Within the limits of this current study, it was feasible to notice that both aging in autoclave for 20h (LTD) and grinding showed not to be detrimental to the mechanical properties of Zirlux FC Y-TZP ceramic.
本研究旨在探讨钻石车针研磨和低温时效对用于整体式牙科修复体的 Y-TZP 陶瓷的机械性能（双轴弯曲强度和结构可靠性）、表面形貌和相转变的影响。根据 ISO 6872（2008）标准制造圆盘状试件（Zirlux FC，Ivoclar Vivadent），并根据两个因素进行分组：“研磨-3 个水平”和“LTD-2 个水平”。研磨在恒温水冷却下使用角向手机进行，使用不同粒度的（超细和粗金刚石车针）。LTD 在 134°C 的高压釜中，2 巴的压力下，20 小时模拟。表面形貌分析表明，基于表面处理粒度，粗糙度增加（粗>X 细>对照），LTD 不影响粗糙度值。研磨和 LTD 均促进 m 相含量增加，尽管观察到不同的降解敏感性。根据现有文献，m 相含量的增加是 Y-TZP 降解的直接指示。威布尔分析表明研磨后特征强度增加（粗=X 细>对照），而对于 LTD，则观察到明显的效果（对照<对照 LTD；X 细=X 细 LTD 和粗=粗 LTD）。所有测试组的威布尔模数在统计学上相似。在本研究的限制范围内，我们可以发现，高压釜中 20 小时时效（LTD）和研磨均不会对 Zirlux FC Y-TZP 陶瓷的机械性能造成不利影响。
