Relative Translucency and Surface Roughness of Four Yttrium-stabilized Tetragonal Zirconia Polycrystalline-based Dental Restorations

Background: Yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP) has become one of the most popular restorative core materials in the last decade due to its high flexural strength and fracture toughness. However, the low translucency of Y-TZP has become a critical issue in shade matching to natural teeth. This study compared the translucency of Y-TZP and alumina core materials at clinically appropriate thicknesses. Methods: Zirconia disc samples were fabricated from Cercon (Dentsply Degudent), Everest (Kavo), Lava (3M ESPE) with 0.5-mm thickness and Procera zirconia (Nobel Biocare) with 0.4-mm thickness. Procera alumina samples with 0.4-mm thickness were also made for comparison. Spectral reflectance of samples was measured and contrast ratios were calculated. Surface roughness (Ra) of all ceramic discs was also analyzed with a Profilometer. Results: One-way ANOVA showed a significantly lower translucency of Cercon than all the other three types of zirconia materials. Procera Alumina also demonstrated significantly higher translucency than all four types of zirconia. The mean Ra of Procera zirconia was significantly higher than the other types of ceramic materials. Conclusion: The Ra of the Procera zirconia group was significantly higher than all the other testing groups.