Objective

To synthesize a zirconia toughened alumina (ZTA) composite with 70% alumina reinforced by 30% zirconia for dental applications and to characterize its microstructure and optical properties for comparison with the isolated counterpart materials and a first-generation 3Y-TZP.

Methods

Disc-shaped specimens were divided in four groups (n = 70/material): (1) 3YSB-E (first generation 3Y-TZP), (2) Zpex (second generation 3Y-TZP), (3) alumina, and (4) ZTA-Zpex 70/30. After synthesis, ceramic powders were pressed, and green-body samples sintered following a predetermined protocol. Specimens were polished to obtain a mirror surface finish. Apparent density was measured by Archimedes principle. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the crystalline content and microstructure. Reflectance tests were performed to determine the contrast-ratio (CR) and translucency-parameter (TP). Mechanical properties were assessed by biaxial flexural strength (BFS) test. All analyses were conducted before and after artificial aging (20 h, 134 °C, 2.2 bar). Optical parameters were evaluated through repeated-measures analysis of variance and Tukey tests (p < 0.05). BFS data were analyzed using Weibull statistics (95% CI).

Results

High density values (95–99%) were found for all ceramic materials and SEM images exhibited a dense microstructure. While XRD patterns revealed the preservation of crystalline content in the ZTA composite, an increase in the monoclinic peak was observed for pure zirconias after aging. Significantly higher CR and lower TP values were observed for the ZTA composite, followed by alumina, 3YSB-E, and Zpex. The highest characteristic stress was recorded for 3YSB-E, followed by intermediate values between ZTA and Zpex, and the lowest for alumina. Aging affected the optical and mechanical properties of both zirconias, while remained stable for ZTA composite and alumina.

Significance

The synthesis of experimental 70−30% ZTA composite was successful and its relevance for dental applications relies on its higher masking ability, aging resistance, and strength similar to zirconia.

中文翻译：

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牙科应用的抗老化ZTA复合材料：微观结构，光学和机械特性。

目的

合成具有70％氧化铝和30％氧化锆增强的氧化铝的氧化锆增韧氧化铝（ZTA）复合材料，用于牙科应用，并表征其微观结构和光学性能，以便与分离的对应材料和第一代3Y-TZP进行比较。

方法

圆盘状样品分为四组（每材料n = 70）：( 1）3YSB-E（第一代3Y-TZP），（2）Zpex（第二代3Y-TZP），（3​​）氧化铝和（ 4）ZTA-Zpex 70/30。合成后，将陶瓷粉末压制，并按照预定规程烧结生坯样品。试样被抛光以获得镜面光洁度。通过阿基米德原理测量表观密度。X射线衍射（XRD）和扫描电子显微镜（SEM）被用来表征晶体含量和微观结构。进行反射测试以确定对比度（CR）和半透明参数（TP）。力学性能通过双轴弯曲强度（BFS）测试进行评估。所有分析均在人工老化（20 h，134°C，2.2 bar）之前和之后进行。光学参数通过方差和Tukey检验的重复测量分析进行评估（p <0.05）。使用威布尔统计数据（95％CI）分析了BFS数据。

结果

发现所有陶瓷材料的高密度值（95-99％），并且SEM图像显示出致密的微观结构。尽管XRD图谱显示ZTA复合材料中的晶体含量得以保留，但观察到老化后纯氧化锆的单斜晶峰增加。ZTA复合材料的CR和TP值均明显较高，其次是氧化铝，3YSB-E和Zpex。3YSB-E记录到最高特征应力，其次是ZTA和Zpex之间的中间值，最低的是氧化铝。老化影响了两种氧化锆的光学和机械性能，同时对于ZTA复合材料和氧化铝保持稳定。

意义

实验性70％至30％ZTA复合材料的合成是成功的，其与牙科应用的相关性取决于其较高的掩盖能力，耐老化性和类似于氧化锆的强度。