The effect of surface treatment and glass-ceramic coating on the wear behavior of different types of zirconia and their antagonists.

Objectives: This in-vitro study aimed to investigate the influence of different pretreatments and surface coatings on the wear of different zirconia and their antagonists.

Method and materials: Zirconia specimens (3-, 4- and 5-mol% yttria tetragonal zirconia; n = 160/material) were subjected to pretreatment (airborne-particle abrasion, 50 µm Al2O3, 1 bar; 120 µm Al2O3, 3 bar; polishing) and surface coating (spray glazing, micro-layering, layering, veneering). References comprised no pretreatment or coating. Wear tests were performed (50 N, 120,000 cycles). Wear (mean, maximum, antagonist) and arithmetic mean roughness Ra and average roughness depth Rz were determined. ANOVA, Bonferroni, and Pearson correlation (α = .05) were performed.

Results: Ra/Rz showed significant (P < .001) differences (Ra: 0.01 ± 0.01 µm to 0.71 ± 0.06 µm; Rz: 0.31 ± 0.09 µm to 4.33 ± 0.44 µm). Two groups could be distinguished by mean and maximum wear with significant (P < .001) differences: (1) glaze sprayed and without coating (mean wear: 9.4 ± 2.6 µm to 57 ± 21.3 µm, max. wear: 24.1 ± 6.9 µm to 125.4 ± 18.2 µm) and (2) all coating procedures (mean wear: 129.2 ± 22.8 µm to 236.5 ± 62.0 µm; max. wear: 188.7 ± 21.4 µm to 444.2 ± 110.6 µm). Antagonist wear (9.2 ± 4.5 to 29.7 ± 5.0%) showed a significant (P < .001) correlation to surface coating, mean and maximum wear, and Ra and Rz. Mean wear significantly (P < .001) correlated with surface coating, maximum wear, and antagonist wear.

Conclusion: Under clinical conditions, layering or veneering can lead to increased wear of the restoration, but in return reduce the abrasion of antagonists. Excessively rough surface treatments should be avoided, as they might increase antagonist wear.