Effect of Erosive‐Abrasive Challenge and Surface Finishing Protocols on Optical Properties and Microhardness of CAD‐CAM Ceramics

Abstract

PURPOSE: To evaluate the effect of erosive-abrasive challenge on the optical properties, microhardness, and surface morphology of CAD-CAM ceramics with different surface finishing protocols. METHODS: CAD-CAM ceramics used were: IPS e.max CAD (DIS), IPS Empress CAD (LEU), Cerec Blocs (FEL), and Celtra Duo (CEL). Specimens were divided into five groups (n = 10): Polishing (P), Conventional Glaze (CG-control), Conventional Glaze with 2 firings (CG₂), Extended Glaze firing (EG), and Extended Glaze with 2 firings (EG₂). An erosive-abrasive challenge was performed with citric acid and simulated toothbrushing. Color change (ΔE₀₀), translucency, contrast ratio, gloss, Vickers microhardness, and surface morphology were evaluated. The evaluations were performed before and after the erosive-abrasive challenge. ΔE₀₀ was analyzed with one-way ANOVA with Welch correction and Games-Howell, while the other data were evaluated with two-way repeated measures ANOVA and Bonferroni post-test (α = 0.05%). RESULTS: After the challenge, CG groups showed clinically unacceptable color changes. Translucency decreased in LEU-P, FEL-P, FEL-EG, and CEL-EG groups, but increased in DIS-CG₂, DIS-EG₂, and CEL-EG groups. The contrast ratio was close to 1. No gloss reduction was observed in CG groups. Microhardness decreased in DIS-EG, DIS-EG₂, LEU, FEL, and CEL groups, but remained unchanged in LEU-CG, FEL-CG₂, and CEL-EG₂ groups. CONCLUSION: Erosive-abrasive challenge affected the properties of CAD-CAM ceramics with different behaviors depending on the surface finishing protocol used. CLINICAL SIGNIFICANCE: The optical properties and microhardness of CAD-CAM ceramics are negatively affected by erosive-abrasive conditions. Manual polishing showed similar performance in maintaining these properties and may represent a viable and effective alternative to glaze application.