High-speed sintering on monolithic zirconia: Effects on surface and antagonist wear in vitro

Purpose: This study aimed to assess the influence of zirconia's chemical structure and the sintering method on the wear behavior of the material itself and the opposing enamel. Materials and Methods: Two different types of zirconia, 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP (Whitepeaks Dental Solutions Inc., Hamminkeln, Germany) and 5 mol% yttria-stabilized tetragonal zirconia polycrystal (5Y-PSZ) (Whitepeaks Dental Solutions Inc., Hamminkeln, Germany), were fabricated via conventional and high-speed sintering methods and investigated for their wear behavior. The two-body wear of zirconia and opposing enamel was induced using a chewing simulation device under a vertical load of 50 N, and a sliding movement of 0.7 mm until 1,200,000 chewing cycles were achieved. A three-dimensional data measuring software (GeoMagic Control X, 2018) was used to calculate volume loss following cyclic fatigue. Two-way ANOVA and Tukey tests analyzed the data. Results: The results demonstrated that both material types, 3Y-TZP and 5Y-PSZ, and the sintering method, conventional or high-speed sintering, significantly affected the wear of enamel and zirconia (p < 0.001). The amount of enamel wear induced by 3Y-TZP and 5Y-PSZ high-speed sintering zirconia was reported to be 502.91 ± 44.91 and 635.07 ± 78.32 µm, respectively, which was significantly higher (p < 0.001) than the same materials when they were sintered conventionally (12.05 ± 0.90 and 13.40 ± 0.65 µm). Comparing the 3Y-TZP and 5Y-TZP high-speed sintered zirconia, the amount of wear of enamel associated with 5Y-PSZ was significantly higher than 3Y-TZP (p < 0.05). When the zirconia wear behavior was evaluated, minor surface loss of less than 15 µm was observed among all the groups. Conclusion: High-speed sintering of zirconia caused substantial enamel loss and minor wear on the zirconia itself. As a result, clinicians may consider using conventionally sintered zirconia to minimize the wear of the antagonist. Clinicians may consider using conventionally sintered zirconia to minimize the wear of the antagonist and avoid the associated clinical complications.