Color and Gloss Stability of CAD-CAM Ceramics After Erosive-Abrasive Challenge

Objectives: Acid erosion is a common issue that can result in the degradation of both dental tissues and restorative materials. This study aimed to evaluate the effect of erosive-abrasive wear on color and gloss stability of CAD-CAM ceramics with varying surface finishes after immersion in extrinsic acid and simulated toothbrushing.
Methods: Specimens were obtained from CAD-CAM blocks: IPS Emax CAD (DIS), IPS Empress CAD (LEU), Cerec Bloc (FEL) and Celtra Duo CAD (CEL) and divided into six groups (n=10): Control (C), Manual Polish (MP), Conventional Glaze (CG), 2-Fire Conventional Glaze (CG₂), Glaze Extended Firing (EG), and 2-Fire Glaze Extended Firing (EG₂). The specimens underwent an erosive-abrasive challenge using citric acid solution (pH 2.6) and a toothbrushing machine simulating 10 years of clinical use. Color parameters (ΔE₀₀, translucency, contrast ratio) and gloss were measured before and after the erosive-abrasive challenge using a reflection spectrophotometer and glossmeter, respectively. Surface morphology was analyzed on additional specimens by scanning electron microscopy. One-way ANOVA with Welch correction and Games-Howell post-test was used for color change and two-way ANOVA for repeated measures post-Bonferroni test for the other properties at a significance level of 5%.
Results: CG groups exhibited color changes exceeding the clinically acceptable threshold (ΔE₀₀>1,8) after the erosive-abrasive challenge. Similarly, C, MP and CG₂ groups of FEL ceramic showed unacceptable color changes. LEU-MP, FEL-MP, FEL-EG and CEL-EG groups showed reduced translucency after the challenge, whereas DIS-CG₂ and DIS-EG₂ showed increased translucency. The contrast ratio remained close to 1 across all groups, regardless of the ceramic type or surface treatment. Gloss reduction was observed in DIS-MP, LEU-EG₂, FEL-MP, FEL-EG₂, CEL-MP, CEL-CG₂ and CEL-EG₂ groups after challenge.
Conclusions: CG groups demonstrated clinically unacceptable color changes after erosive-abrasive challenge, while changes in translucency and gloss were influenced by the specific surface treatment applied to each ceramic.