Department of Prosthodontics and Periodontology, University of São Paulo - Bauru School of Dentistry, Bauru, SP, Brazil.
Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY, USA; Hansjörg Wyss Department of Plastic Surgery, NYU Langone Medical Center, New York, NY, USA; Mechanical and Aerospace Engineering, NYU Tandon School of Engineering, New York, NY, USA.
Dent Mater. 2020 Dec;36(12):e365-e374. doi: 10.1016/j.dental.2020.08.010. Epub 2020 Sep 15.
To evaluate the effect of aging on the microstructural, mechanical, and optical properties of an experimental zirconia-toughened alumina composite with 80%AlO and 20%ZrO (ZTA Zpex) compared to a translucent zirconia (Zpex) and Alumina.
Disc-shaped specimens were obtained by uniaxial and isostatic pressing the synthesized powders (n = 70/material). After sintering and polishing, half of the specimens underwent aging (20 h, 134 °C, 2.2 bar). Crystalline content and microstructure were evaluated using X-ray diffraction and scanning electron microscopy, respectively. Specimens underwent biaxial flexural strength testing to determine the characteristic stress, Weibull modulus, and reliability. Translucency parameter (TP) and Contrast ratio (CR) were calculated to characterize optical properties.
ZTA Zpex demonstrated a compact surface with a uniform dispersion of zirconia particles within the alumina matrix, and typical alumina and zirconia crystalline content. ZTA Zpex and alumina exhibited higher CR and lower TP than Zpex. ZTA Zpex and Zpex showed significantly higher characteristic stress relative to alumina. While aging did not affect optical and mechanical properties of ZTA Zpex and alumina, Zpex demonstrated a significant increase in translucency, as well as a in characteristic stress. Alumina reliability was significantly lower than others at 300 MPa, ZTA Zpex and Zpex reliability decreased at 800 MPa, except for aged Zpex.
While aging did not affect the mechanical nor the optical properties of ZTA Zpex and alumina, it did alter both properties of Zpex. The results encourage further investigations to engineer ZTA as a framework material for long span fixed dental prostheses specially where darkened substrates, such as titanium implant abutments or endodontically treated teeth, demand masking.
评估老化对 80%AlO 和 20%ZrO（ZTA Zpex）实验氧化锆增韧氧化铝复合材料与半透明氧化锆（Zpex）和氧化铝微观结构、力学和光学性能的影响。
通过单轴和等静压将合成粉末（n = 70/材料）制成圆盘形试件。烧结和抛光后，一半的试件进行老化（20 h，134°C，2.2 bar）。使用 X 射线衍射和扫描电子显微镜分别评估晶体含量和微观结构。对试件进行双向弯曲强度测试，以确定特征应力、威布尔模量和可靠性。计算透光率参数（TP）和对比度比（CR）以表征光学性能。
ZTA Zpex 表面致密，氧化锆颗粒在氧化铝基体中均匀分散，具有典型的氧化铝和氧化锆晶体含量。ZTA Zpex 和氧化铝的 CR 较高，TP 较低。ZTA Zpex 和 Zpex 的特征应力明显高于氧化铝。虽然老化不影响 ZTA Zpex 和氧化铝的光学和力学性能，但 Zpex 的透光率显著增加，特征应力也显著增加。氧化铝在 300 MPa 时可靠性明显低于其他材料，ZTA Zpex 和 Zpex 在 800 MPa 时可靠性降低，除了老化的 Zpex。
虽然老化不影响 ZTA Zpex 和氧化铝的力学和光学性能，但它确实改变了 Zpex 的这两种性能。研究结果鼓励进一步研究，将 ZTA 工程化为长跨度固定义齿修复体的框架材料，特别是在需要掩蔽钛种植体基台或牙髓治疗牙齿等暗化基底的情况下。
