Effect of staining beverages on color stability and surface roughness of additively manufactured permanent resin materials

OBJECTIVE: To evaluate the effects of commonly consumed staining beverages on the color stability and surface roughness of two additively manufactured permanent resin restorative materials. MATERIALS AND METHODS: Sixty disk-shaped specimens (10 mm × 2 mm) were fabricated from two additively manufactured resin materials (Saremco Print Crowntec and VarseoSmile Crown Plus). Specimens were finished with standardized polishing procedures and color values (CIE L*a*b*) and baseline surface roughness (Ra) were recorded. Samples were randomly assigned to three immersion media (tea, coffee, distilled water; n = 10 per subgroup) and stored at 37 °C for 14 days with daily solution renewal. Color measurements were repeated after 24 h and 14 days, and color differences were calculated using the CIEDE2000 formula (ΔE₀₀). Surface roughness was re-measured after 14 days. Data were analyzed using mixed-model ANOVA and correlation tests (α = 0.05). RESULTS: Staining solution significantly affected color change at both evaluation periods (p < 0.001), while material type had no significant influence (p > 0.05). Tea produced the highest discoloration values, followed by coffee, whereas water groups remained below acceptability thresholds. Color change increased significantly over time in tea and coffee groups. Surface roughness showed only minimal changes after immersion, with Ra values ranging from 0.438 to 0.559 μm at baseline and 0.444-0.567 μm after 14 days, with no significant effects of material or staining solution (p > 0.05). No significant correlation was found between baseline surface roughness and final color change (p > 0.05). A significant positive correlation was observed between the change in surface roughness (ΔRa) and color change (ΔE00) (p < 0.05). CONCLUSIONS: Discoloration of additively manufactured permanent resin materials was primarily influenced by exposure to staining beverages. Tea and coffee caused clinically noticeable color changes, while surface roughness showed limited changes during short-term aging. However, a significant positive correlation between surface roughness change and color change suggests that surface degradation may contribute to staining susceptibility.