IADR Abstract Archives
Compositional, Optical and Mechanical Properties of New Multi-layered Dental Zirconia
Objectives: To investigate the composition, mechanical, and optical properties of three novel multi-layered zirconias with different translucency levels.
Methods: Ultra-translucent Multi-layered (UTML), Super-translucent Multi-layered (STML), and Multi-layered (ML) zirconias (Katana, Kuraray) were evaluated. Bars (25×2×3 mm3) and plates (15×15×1 mm3) were cut from top and bottom layers of the CAD/CAM blocks. Sintering was carried out at 1550°C for 2h for UTML and STML, and at 1500°C for 2h for ML. Samples were then polished down to 0.5 µm finish. Bar specimens were fractured in 4-point-bending test to calculate flexural strength. Color coordinates (CIELab) were measured on plate specimens over white and black backgrounds with a coupling agent (glycerol) to calculate the translucency parameter (TP). Material characterizations were performed under scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF).
Results: Chemical characterization revealed that, within each material, zirconia composition is the same throughout the layers, being 5Y-TZP for UTLM, 4Y-TZP for STML and 3Y-TZP for ML. Correspondingly, the top and bottom layers of each material have similar mechanical behavior. The increased yttria content among materials is associated with increased cubic zirconia phase. However, flexural strength is similar between 4Y-TZP and 5Y-TZP. Besides, UTML has a significantly higher TP in the top layer. STML shows similar TP between layers and ML shows the least TP value.
Conclusions: New multi-layered zirconia shows a trade-off between the strength and the translucency.
Methods: Ultra-translucent Multi-layered (UTML), Super-translucent Multi-layered (STML), and Multi-layered (ML) zirconias (Katana, Kuraray) were evaluated. Bars (25×2×3 mm3) and plates (15×15×1 mm3) were cut from top and bottom layers of the CAD/CAM blocks. Sintering was carried out at 1550°C for 2h for UTML and STML, and at 1500°C for 2h for ML. Samples were then polished down to 0.5 µm finish. Bar specimens were fractured in 4-point-bending test to calculate flexural strength. Color coordinates (CIELab) were measured on plate specimens over white and black backgrounds with a coupling agent (glycerol) to calculate the translucency parameter (TP). Material characterizations were performed under scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF).
Results: Chemical characterization revealed that, within each material, zirconia composition is the same throughout the layers, being 5Y-TZP for UTLM, 4Y-TZP for STML and 3Y-TZP for ML. Correspondingly, the top and bottom layers of each material have similar mechanical behavior. The increased yttria content among materials is associated with increased cubic zirconia phase. However, flexural strength is similar between 4Y-TZP and 5Y-TZP. Besides, UTML has a significantly higher TP in the top layer. STML shows similar TP between layers and ML shows the least TP value.
Conclusions: New multi-layered zirconia shows a trade-off between the strength and the translucency.