Effects of Erosive-Abrasive Wear and Repolishing on CAD-CAM Ceramics Properties

Objectives: Erosive-abrasive wear can compromise the integrity of ceramic-based materials, and a consensus on the best repair approach remains elusive. This study evaluated the effects of erosive-abrasive wear and repolishing on optical and surface properties of CAD-CAM ceramics.
Methods: Specimens were obtained from three CAD-CAM blocks (n = 10): IPS Emax CAD (DL), IPS Empress CAD (LE), Cerec Bloc (FE). Measurements were conducted at three time-points: after initial polishing, after erosive-abrasive wear, and after repolishing. Ceramic polishing and repolishing were performed using silicone polishers (Ceramisté system, SHOFU). Erosive-abrasive wear was simulated using hydrochloric acid immersion (pH 1.2) and a toothbrushing machine to replicate three years of clinical use. Optical properties (color change, translucency, opalescence, contrast ratio) and surface properties (roughness) were analyzed using a digital spectrophotometer and a roughness tester, respectively. Statistical tests included two-way repeated-measures ANOVA with Bonferroni post-test at a significance level of 5%.
Results: After repolishing, only FE showed perceptible color changes that exceeded clinically acceptable thresholds (ΔE₀₀). Within each CAD-CAM ceramic, translucency and contrast ratio were unaffected by erosive-abrasive wear and repolishing. Opalescence was similar among all ceramics, regardless of the evaluation time-point. Repolishing after erosive-abrasive wear reduced surface roughness across all ceramics.
Conclusions: In conclusion, feldspathic ceramic appears to be more susceptible to erosive-abrasive wear. Ceramic repolishing after erosive-abrasive wear reduced surface roughness and showed limited efficacy in reversing color changes. No effects on translucency, opalescence, or contrast ratio were observed for any CAD-CAM ceramic regardless of the surface treatment.