Impact of High-Speed Sintering on Accuracy and Fit of 4 mol% Yttria-Stabilized Tetragonal Zirconia Polycrystals

Purpose: To investigate the impact of high-speed sintering on the accuracy (ie, trueness and reproducibility) and fit of yttria-stabilized tetragonal zirconia polycrystal (4Y-TZP) full-coverage single-unit fixed dental prostheses (FDPs) and three-unit FDPs. Materials and Methods: Single-unit FDPs, conventional three-unit FDPs, and cantilever three-unit FDPs (N = 108; n = 12 per subgroup) were fabricated from: (1) high-speed-sintered (1,580 degrees C, about 20 minutes) multi-layer 4Y-TZP (Zolid RS [ZMLH]), as well as two conventionally sintered (1,450 degrees C, about 10 hours) materials: (2) multi-layer 4Y-TZP (Zolid Gen-X [ZMLC]) and (3) monochrome 4Y-TZP (Ceramill Zolid HT+ PS [ZMOC]). All specimens were scanned, and trueness, reproducibility, and fit were measured with 3D analysis software. For data analysis, Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests were performed (alpha = .05). Results: Three-unit FDPs made from ZMLH presented a deterioration of accuracy in comparison to ZMLC (P <= .001 to .008). The influence of high-speed sintering on marginal and general fit was not clinically relevant (P = .154 to .877). Conclusion: High-speed sintering influenced the accuracy of 4Y-TZP full-coverage single-unit and three-unit FDPs. However, no clinically relevant impact on fit was observed.