Effects of Simulated Gastric Acid Exposure on Surface Roughness, Optical Properties, and Mass Change in Monolithic CAD/CAM Restorative Materials: An In Vitro Study

This in vitro study evaluated the effects of simulated gastric acid exposure on surface roughness, color change, translucency, and mass change in four monolithic CAD/CAM restorative materials with different microstructural compositions. Rectangular specimens (12 × 14 × 1 mm; n = 12/group) were prepared from a polymer-infiltrated ceramic network material (VITA Enamic), a zirconia-reinforced lithium silicate glass-ceramic (Celtra Duo), a resin nanoceramic (Cerasmart), and a lithium disilicate glass-ceramic (IPS e.max CAD). After standardized finishing and polishing, baseline measurements of surface roughness, color coordinates, translucency, and mass were obtained, and the specimens were then individually immersed in simulated gastric acid (0.06 M HCl, pH 1.2) at 37 °C for 96 h, with the solution renewed every 24 h. Post-exposure measurements were performed using the same protocols. Data were analyzed using the Shapiro–Wilk test, Kruskal–Wallis test with Dunn’s post hoc comparisons, and Wilcoxon signed-rank test (α = 0.05). Significant changes were observed after acid exposure, and the magnitude of these changes varied among materials. Surface roughness increased significantly in all groups, with the greatest increase detected in Celtra Duo and VITA Enamic. Measured mass also changed significantly in all groups; VITA Enamic showed a slight increase, whereas Celtra Duo, Cerasmart, and IPS e.max CAD showed slight decreases. Although statistically significant differences in color change and translucency were identified among the groups, all color changes remained below the clinically perceptible threshold, indicating limited optical impact under the present model. IPS e.max CAD exhibited the lowest color change, whereas Cerasmart showed the highest ΔE00 values. Within the limitations of this accelerated in vitro model, simulated gastric acid exposure caused material-dependent alterations in surface roughness, limited optical changes, and small measured mass changes in monolithic CAD/CAM restorative materials.