Flask Joseph D, Thompson Geoffrey A, Singh Maharaj, Berzins David W
Graduate student of Dental Biomaterials, Department of General Dental Sciences, Marquette University School of Dentistry, Milwaukee, Wis.
Professor, Graduate Prosthodontics, Department of General Dental Sciences, Marquette University School of Dentistry, Milwaukee, Wis.
J Prosthet Dent. 2022 May;127(5):793-800. doi: 10.1016/j.prosdent.2020.12.009. Epub 2021 Feb 11.
More translucent dental zirconias have been developed by incorporating the cubic phase and reducing the tetragonal phase content that undergoes transformation toughening, leading to reduced mechanical properties. Whether the clinically relevant mechanical property of the edge chipping toughness of the material is also reduced is unclear.
The purpose of this in vitro study was to evaluate the edge chipping toughness and translucency of translucent zirconia, 3mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP), and lithium disilicate.
Two translucent zirconia products, Katana and Lava Esthetic; one 3Y-TZP, Lava Plus; and one lithium disilicate, IPS e.max Press were prepared and tested for phase composition via X-ray diffraction (XRD) (n=3), translucency via a spectrophotometer (n=20), and edge chipping via a universal testing machine with a custom-machined specimen holder and diamond indenter (n=20). The 3Y-TZP and lithium disilicate served as the optimal control materials for edge chipping and translucency, respectively. Translucency was compared with 1-way ANOVA and edge toughness with ANCOVA (α=.05).
The XRD showed the 3Y-TZP to be almost completely tetragonal phase compared with the 2 translucent zirconia products that were predominantly cubic. Katana UTML and IPS e.max Press had a statistically similar (P>.05) translucency that was significantly (P<.05) greater than that of Lava Esthetic and Lava Plus. The edge toughness of Katana UTML was 304 N/mm, IPS e.max Press was 354 N/mm, Lava Esthetic was 394 N/mm, and Lava Plus was 717 N/mm, with significance rankings of Katana UTM<IPS e.max Press=Lava Esthetic<Lava Plus.
Some translucent zirconias had translucency similar to that of lithium disilicate; however, as translucency increased with increased cubic content, edge toughness decreased.
通过引入立方相并减少经历相变增韧的四方相含量，已开发出更半透明的牙科氧化锆，但这导致机械性能降低。尚不清楚该材料的边缘崩裂韧性这一临床相关机械性能是否也会降低。
本体外研究的目的是评估半透明氧化锆、3摩尔％氧化钇稳定的四方氧化锆多晶体（3Y-TZP）和二硅酸锂的边缘崩裂韧性和半透明度。
制备了两种半透明氧化锆产品，Katana和Lava Esthetic；一种3Y-TZP，Lava Plus；以及一种二硅酸锂，IPS e.max Press，并通过X射线衍射（XRD）（n = 3）测试相组成，通过分光光度计（n = 20）测试半透明度，通过配备定制加工试样架和金刚石压头的万能试验机（n = 20）测试边缘崩裂。3Y-TZP和二硅酸锂分别作为边缘崩裂和半透明度的最佳对照材料。半透明度采用单因素方差分析进行比较，边缘韧性采用协方差分析（α = 0.05）。
XRD显示，与主要为立方相的两种半透明氧化锆产品相比，3Y-TZP几乎完全是四方相。Katana UTML和IPS e.max Press的半透明度在统计学上相似（P>0.05），且显著高于（P<0.05）Lava Esthetic和Lava Plus。Katana UTML的边缘韧性为304 N/mm，IPS e.max Press为354 N/mm，Lava Esthetic为394 N/mm，Lava Plus为717 N/mm，显著性排名为Katana UTM<IPS e.max Press = Lava Esthetic<Lava Plus。
一些半透明氧化锆的半透明度与二硅酸锂相似；然而，随着立方相含量增加半透明度提高，边缘韧性降低。
