Lim Chek Hai, Alves Larissa M M, Vardhaman Sonaj, Bonfante Estevam A, Kim Do Kyung, Zhang Yu
Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, PA 19104, USA.
Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, PA 19104, USA; Department of Prosthodontics and Periodontology, Bauru School of Dentistry, University of São Paulo (USP), Bauru, SP, Brazil.
Dent Mater. 2025 Feb;41(2):194-202. doi: 10.1016/j.dental.2024.11.008. Epub 2024 Dec 4.
This study aimed to elucidate the effect of various two-step sintering (TSS) protocols on the physical, mechanical, and optical properties of partially stabilized zirconia with different yttria dopant concentrations (Y-PSZ).
Disc-shaped specimens were obtained from most widely used commercial dental zirconia powders of various Y contents (Tosoh Corp.) by uniaxial pressing followed by cold-isostatic pressing. Densification was carried out using TSS protocols with varying temperatures for both sintering steps. Relative density (ρ), microstructure, and phase content were analyzed. Biaxial flexural strength (σ) and translucency parameter (TP) were evaluated.
The TSS results were compared with optimized conventional sintering (CS) results from a previous study for the same Y-PSZ compositions. TSS 3Y-PSZ and 4Y-PSZ reached similar ρ to those of their CS counterparts, whereas 5Y-PSZ failed to achieve that regardless of TSS protocol. TSS yielded less cubic phase compared to CS, especially for 3Y-PSZ and for higher temperatures. TSS suppressed the grain growth throughout the temperature range investigated, promoting smaller grains than CS (p < 0.05). The TP values for TSS Y-PSZ were lower than those of CS (p ≤ 0.0001), except for 3Y-PSZ. The σ values for TSS Y-PSZ were significantly higher than those of CS (p ≤ 0.0002).
TSS increased strength without significantly jeopardizing the optical properties of various Y-PSZ compositions relative to their CS counterparts. This alternative sintering method appears to be a promising technique for controlling grain growth while eliminating porosities in dental Y-PSZ ceramics, thus potentially enhancing the clinical longevity of zirconia restorations.
本研究旨在阐明各种两步烧结（TSS）方案对不同氧化钇掺杂浓度（Y-PSZ）的部分稳定氧化锆的物理、机械和光学性能的影响。
通过单轴压制然后冷等静压，从不同Y含量（东曹公司）的最广泛使用的商用牙科氧化锆粉末中获得圆盘形试样。使用TSS方案在两个烧结步骤中采用不同温度进行致密化。分析相对密度（ρ）、微观结构和相含量。评估双轴弯曲强度（σ）和半透明参数（TP）。
将TSS结果与先前研究中相同Y-PSZ成分的优化传统烧结（CS）结果进行比较。TSS 3Y-PSZ和4Y-PSZ的ρ与它们的CS对应物相似，而5Y-PSZ无论采用何种TSS方案都未能达到。与CS相比，TSS产生的立方相较少，特别是对于3Y-PSZ和较高温度。在整个研究温度范围内，TSS抑制了晶粒生长，促进了比CS更小的晶粒（p < 0.05）。TSS Y-PSZ的TP值低于CS（p≤0.0001），3Y-PSZ除外。TSS Y-PSZ的σ值显著高于CS（p≤0.0002）。
相对于其CS对应物，TSS提高了强度，而没有显著损害各种Y-PSZ成分的光学性能。这种替代烧结方法似乎是一种有前途的技术，可用于控制牙科Y-PSZ陶瓷中的晶粒生长并消除孔隙，从而有可能提高氧化锆修复体的临床使用寿命。
