Beverage-Induced Discoloration and Surface Degradation of Single-Shade Composite Resin: An In Vitro Investigation

The longevity of direct composite resin restorations depends critically upon maintaining color stability and surface integrity throughout their clinical service life. Single-shade composite resins, which utilize optical blending technology rather than conventional pigmentation, have been introduced to streamline restorative procedures. However, limited evidence exists regarding their susceptibility to extrinsic staining and surface degradation when exposed to acidic and chromogenic beverages commonly consumed in modern diets.

This study aimed to evaluate and compare the effects of commonly consumed acidic and chromogenic beverages on the color stability and surface roughness of a single-shade composite resin using spectrophotometric analysis and three-dimensional optical profilometry.

Forty disc-shaped single-shade composite resin specimens were made and divided into four groups (n = 10) at random: artificial saliva, kombucha, apple cider, and white wine. Specimens underwent daily 24-h immersion cycles at 37°C in their respective solutions. Commission Internationale de l'Éclairage (CIE) LAB was used to measure color coordinates (L ^∗, a ^∗, and b ^∗) colorimetry at baseline, 7 days, and 14 days. Surface roughness (Sp, Sv, Sz, and surface skewness [Ssk]) was assessed using three-dimensional optical profilometry at baseline and 28 days. Statistical analysis employed within-group comparisons using paired t-tests and one-way analysis of variance (ANOVA) with Tukey post hoc testing (α = 0.05).

In comparison to all other groups, kombucha significantly increased color change (ΔE) at 7 days (p < 0.001). By 14 days, all three test beverages produced statistically significant discoloration relative to artificial saliva, with kombucha demonstrating the highest ΔE values (p < 0.001). Analysis of CIE LAB coordinates revealed predominantly positive Δ b ^∗ values in all beverage groups, indicating yellow-ward discoloration. White wine produced the most pronounced increase in surface roughness parameters at 28 days (p = 0.016), followed by apple cider, while kombucha showed intermediate roughness alterations despite the greatest color change.

Under the conditions of this investigation, single-shade composite resin exhibits measurable and clinically significant changes in both color stability and surface topography following exposure to acidic and chromogenic beverages. The dissociation between staining severity and surface roughness alteration suggests distinct degradation mechanisms. These results highlight the need for dietary counseling and preventive measures to maximize the long-term functional and esthetic performance of single-shade composite restorations, which has significant implications for clinical practice.