Effect of an alginate-based antacid and simulated gastric acid on the surface roughness and color stability of CAD/CAM resin-based materials

This in vitro study aimed to evaluate the effect of simulated gastric fluid (SGF) and an alginate-based antacid on the surface roughness and color stability of two additively manufactured (AM) and one subtractively manufactured (SM) resin-based restorative materials. A total of 168 disc-shaped specimens (10 × 2 mm) were fabricated from two AM resin composites (Bego VarseoSmile TriniQ [AM-VS] and Saremco Crowntec [AM-C]) and one SM nano-ceramic hybrid (Voco Grandio blocs [SM-V]). Specimens were distributed into seven subgroups (n = 8) based on immersion media: distilled water (control); SGF mixed with artificial saliva (AS) at ratios of 1:1, 1:3, and 1:5; and the same mixtures with 10% alginate-based antacid (Gaviscon®). All solutions were refreshed daily and maintained at 37 °C with gentle agitation for 48 h. Surface roughness (Ra) was measured with a contact profilometer, and color stability (ΔE₀₀) was assessed with a spectrophotometer. Data were analyzed using mixed-model ANOVA and post hoc tests (α = 0.05). Immersion in SGF + AS increased ΔE₀₀ and Ra values in all materials compared with distilled water (p<.001). The highest color change was observed in AM-C at SGF + AS (1:5) (1.87 ± 0.30), whereas SM-V showed the lowest ΔE₀₀ values (1.55 ± 0.04). Surface roughness increased under acidic conditions, with AM-C exhibiting the highest Ra values (1.30 ± 0.02 μm). The alginate-based antacid significantly reduced Ra values for all materials and reduced ΔE₀₀ values in AM-C (1:3 and 1:5) and AM-VS (1:5) (p<.05), with selected antacid-containing subgroups showing values approaching those of the control. Simulated gastric fluid compromised the surface integrity and color stability of CAD/CAM resin-based restorative materials, with material-dependent differences. The addition of an alginate-based antacid mitigated these effects under selected experimental conditions, suggesting a potential protective role against acid-induced degradation.