Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, USA.
Department of Biomaterials and Biomimetics, New York University College of Dentistry, New York, USA; Graduate Program in Dentistry, Positivo University, Curitiba, Brazil.
Dent Mater. 2019 May;35(5):797-806. doi: 10.1016/j.dental.2019.02.017. Epub 2019 Mar 7.
To fully realize the range of indication and clinical advantages of the new multi-layered zirconias, a comprehensive understanding of their chemical composition, microstructure, low temperature degradation (LTD) resistance, and translucency properties is paramount.
A zirconia system (Katana, Kuraray Noritake), including 3 distinct grades of multi-layered zirconias, was selected for study: Ultra Translucent Multi-layered zirconia (UTML), Super Translucent Multi-layered zirconia (STML), and Multi-layered zirconia (ML). For different materials and their individual layers, the chemical composition, zirconia phase fractions, and microstructure were determined by X-ray fluorescence (XRF), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). Also, their resistance to LTD and translucency properties were characterized.
Our findings revealed no major differences amongst layers, but the 3 materials were very distinct-UTML: 5Y-PSZ (5 mol% yttria-partially-stabilized zirconia) with ˜75 wt% cubic content and a 4.05 (±0.85) μm average grain size, STML: 4Y-PSZ with ˜65 wt% cubic content and a 2.81 (±0.17) μm average grain size, and ML: 3Y-PSZ with <50 wt% cubic content and a 0.63 (±0.03) μm average grain size. After water aging at 120 °C for 12 h, greater monoclinic content was found in ML. UTML and STML did not show detectable monoclinic phase. The translucency was similar among layers, and also between UTML and STML, which were superior to ML.
For each multi-layered zirconia grades, the layers are only differed in pigment types and contents, which yield remarkably natural shade gradients. Also, despite the significant compositional difference between STML and UTML, both materials showed similar translucencies.
为了充分了解新型多层氧化锆的适应证范围和临床优势，必须全面了解其化学成分、微观结构、低温降解（LTD）抗性和透光性。
选择了一种氧化锆系统（Katana，Kuraray Noritake），包括 3 种不同等级的多层氧化锆：超透明多层氧化锆（UTML）、超透明多层氧化锆（STML）和多层氧化锆（ML）。对于不同的材料及其各个层，通过 X 射线荧光（XRF）、X 射线衍射（XRD）和场发射扫描电子显微镜（FE-SEM）确定化学成分、氧化锆相分数和微观结构。还对其 LTD 抗性和透光性进行了表征。
我们的研究结果表明各层之间没有明显差异，但这 3 种材料之间的差异非常明显-UTML：5Y-PSZ（5mol%氧化钇部分稳定氧化锆），立方含量约为 75wt%，平均晶粒尺寸为 4.05（±0.85）μm，STML：4Y-PSZ，立方含量约为 65wt%，平均晶粒尺寸为 2.81（±0.17）μm，ML：3Y-PSZ，立方含量小于 50wt%，平均晶粒尺寸为 0.63（±0.03）μm。在 120°C 下进行 12 小时水老化后，发现 ML 的单斜相含量更高。ML 未检测到可检测的单斜相。各层之间的透光率相似，UTML 和 STML 之间的透光率也相似，均优于 ML。
对于每一种多层氧化锆等级，各层之间仅在颜料类型和含量上有所不同，从而产生了非常自然的色调梯度。此外，尽管 STML 和 UTML 之间存在显著的化学成分差异，但这两种材料都表现出相似的透光率。
