Microstructural, mechanical, and optical characterization of an experimental aging-resistant zirconia-toughened alumina (ZTA) composite.,Dental Materials

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Microstructural, mechanical, and optical characterization of an experimental aging-resistant zirconia-toughened alumina (ZTA) composite.
Dental Materials ( IF 5 ) Pub Date : 2020-09-15 , DOI: 10.1016/j.dental.2020.08.010
A C O Lopes ₁ , P G Coelho ₂ , L Witek ₃ , E B Benalcázar Jalkh ₄ , L A Gênova ₅ , K N Monteiro ₆ , P F Cesar ₆ , P N Lisboa-Filho ₇ , E T P Bergamo ₁ , I S Ramalho ₁ , T M B Campos ₈ , E A Bonfante ₁

Affiliation

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.
Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, NY, USA.
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.
Institute of Research in Nuclear Energy, SP, Brazil.
Department of Biomaterials and Oral Biology, University of São Paulo, School of Dentistry, SP, Brazil.
Department of Physics, São Paulo State University, Bauru, SP, Brazil.
Physics Departament, Aeronautics Technological Institute (ITA), São José dos Campos, SP, Brazil.

Objective

To evaluate the effect of aging on the microstructural, mechanical, and optical properties of an experimental zirconia-toughened alumina composite with 80%Al₂O₃ and 20%ZrO₂ (ZTA Zpex) compared to a translucent zirconia (Zpex) and Alumina.

Methods

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.

Results

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.

Significance

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.

中文翻译：

实验性耐老化氧化锆增韧氧化铝（ZTA）复合材料的微观结构，机械和光学特性。

目的

为了评估时效对半透明氧化锆（Zpex）和氧化铝相比，含80％Al ₂ O ₃和20％ZrO ₂（ZTA Zpex）的氧化锆增韧氧化铝复合材料的微观结构，机械和光学性能的影响。

方法

通过单轴和等静压合成粉末（n = 70 /材料）获得圆盘状样品。烧结和抛光后，一半样品进行老化（20 h，134°C，2.2 bar）。分别使用X射线衍射和扫描电子显微镜评估晶体含量和微观结构。标本进行了双轴弯曲强度测试，以确定特征应力，威布尔模量和可靠性。计算半透明参数（TP）和对比度（CR）以表征光学性质。

结果

ZTA Zpex展示了致密的表面，氧化锆颗粒在氧化铝基质中均匀分散，并且具有典型的氧化铝和氧化锆晶体含量。ZTA Zpex和氧化铝比Zpex具有更高的CR和更低的TP。ZTA Zpex和Zpex相对于氧化铝显示出明显更高的特征应力。尽管时效不会影响ZTA Zpex和氧化铝的光学和机械性能，但Zpex的透光率和特征应力均显着提高。在300 MPa时，氧化铝的可靠性显着低于其他氧化铝，ZTA Zpex和Zpex的可靠性在800 MPa时均下降，但老化的Zpex除外。