The coloring process of monolithic dental zirconia caused considerable debate on the possible effects of different coloring methods. The main objective of this study was to investigate the influence of pigments in 3 multilayer 5-mol% yttria partially stabilized zirconia (5Y-PSZ) disks (Lava Esthetic A2 [Zr-AGG_A2] and Bleach [Zr-AGG_BL], both 3M Oral Care, and Katana STML A2 [Zr-NoAGG], Kuraray Noritake). The influence of pigment addition on the translucency parameter (TP00), fracture toughness, Vickers hardness, biaxial strength, and hydrothermal stability was assessed and correlated with the microstructure and phase composition. The pigment composition and distribution were evaluated by light and fluorescence microscopy, electron probe microanalysis, and nano–scanning electron microscopy. The chemical and phase composition and aging behavior were assessed using X-ray fluorescence and X-ray diffraction, respectively, while the aging sensitivity of the pigments was evaluated using micro-Raman spectroscopy. In contrast to Zr-NoAGG, possessing a typical 5Y-PSZ microstructure, the pigment additions in both Zr-AGG_A2/BL zirconia resulted in large yellow and blue fluorescent Er-, Hf-, and Al-containing agglomerates composed of small grains (0.57 µm and 0.38 µm, respectively, vs. 0.92 µm for the surrounding grains) with lower Y2O3 content. Zr-AGG_A2 had the lowest aging resistance, with transformation degradation occurring exclusively within the pigment agglomerates. All zirconia grades had a high Y2O3 content (4.2%–5.7 mol%) tetragonal ZrO2 phase and a high (42%–55 wt%) cubic ZrO2 phase content. Although no statistical differences were measured for hardness and toughness, Zr-NoAGG had a significantly higher TP00, higher flexural strength, and lower mechanical reliability compared to both Zr-AGG_A2/BL zirconia. The rare-earth oxide-containing zirconia agglomerates that were added as pigments to the multilayered monolithic Zr-AGG_A2/BL zirconia are the cause for their lower optical and mechanical properties and reduced aging resistance.

中文翻译：

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多层氧化锆着色可能会影响其光学和机械性能


整体式牙齿氧化锆的着色过程引起了关于不同着色方法可能产生的影响的相当大的争论。本研究的主要目的是研究颜料在 3 个多层 5-mol% 氧化钇部分稳定氧化锆 （5Y-PSZ） 盘（熔岩美学 A2 [Zr-AGG_A2] 和漂白剂 [Zr-AGG_BL]，均为 3M 口腔护理，以及武士刀 STML A2 [Zr-NoAGG]，可乐丽则武）。评估了颜料添加对半透明性参数 （TP00） 、断裂韧性、维氏硬度、双轴强度和水热稳定性的影响，并与微观结构和物相组成相关联。通过光学和荧光显微镜、电子探针微量分析和纳米扫描电子显微镜评估色素组成和分布。分别使用 X 射线荧光和 X 射线衍射评估化学和物相组成以及老化行为，而使用显微拉曼光谱评估颜料的老化敏感性。与具有典型 5Y-PSZ 微观结构的 Zr-NoAGG 相比，Zr-AGG_A2/BL 氧化锆中的颜料添加导致含有 Er-、Hf 和 Al 的大荧光团聚体由小颗粒（分别为 0.57 μm 和 0.38 μm，而周围颗粒为 0.92 μm）组成，Y2O3 含量较低。Zr-AGG_A2 具有最低的抗老化性，转变降解仅发生在颜料团聚体内。所有氧化锆等级均具有高 Y2O3 含量 （4.2%–5.7 mol%） 的四方 ZrO2 相和高 （42%–55 wt%） 立方 ZrO2 相含量。 虽然没有测量硬度和韧性的统计差异，但与 Zr-AGG_A2/BL 氧化锆相比，Zr-NoAGG 具有明显更高的 TP00、更高的弯曲强度和较低的机械可靠性。作为颜料添加到多层整体 Zr-AGG_A2/BL 氧化锆中，含稀土氧化物的氧化锆附聚体是其光学和机械性能较低以及耐老化性降低的原因。