Effect of Hydrothermal Aging on Translucency, Phase Transformation, and Mechanical Properties of Multilayer Monolithic Zirconia Materials

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Alkurt M., Uulu M. A.

Journal of Functional Biomaterials, cilt.17, sa.11, ss.1-23, 2026 (SCI-Expanded)

Özet

Background/Objectives: This in-vitro study aimed to evaluate the effects of hydrothermal aging on translucency, phase transformation, surface topography, surface hardness, and biaxial flexural strength. Methods: Three multilayered zirconia materials (Katana Zirconia, Kuraray Noritake), namely Ultra Translucent Multi-Layered (UTML), Super Translucent Multi-Layered (STML), and Multi-Layered (ML), were evaluated. Each material was divided into control, 5-h, and 10-h hydrothermal aging groups. A total of 81 specimens (n = 9 per subgroup) were evaluated. The specimens were evaluated using spectrophotometry, XRD, SEM, Vickers hardness, and biaxial flexural strength tests. Data were analyzed using two-way ANOVA and three-way mixed-design ANOVA, followed by Tukey’s post-hoc test (α = 0.05). Results: Material type (p < 0.001), hydrothermal aging duration (p = 0.023), and measurement time (p < 0.001) significantly affected translucency. A significant interaction between aging duration and measurement time was also observed (p = 0.002), with a greater reduction in TP after 10 h than after 5 h of aging. Hydrothermal aging did not significantly affect Vickers hardness (p > 0.05), whereas material type had a significant effect (p < 0.05), with UTML exhibiting significantly higher hardness than ML. Hydrothermal aging increased the monoclinic phase content in all materials, with ML showing the greatest transformation. Biaxial flexural strength was significantly affected by material type and aging duration (p < 0.05), with ML exhibiting the highest strength and an overall increase following aging. Conclusions: Hydrothermal aging significantly reduced the translucency of the multilayered zirconia materials. Phase transformation was more pronounced in ML than in UTML and STML. ML exhibited the highest biaxial flexural strength, whereas UTML showed the lowest. Overall, hydrothermal aging increased biaxial flexural strength, although the response varied among materials.