Evaluation of the Effect of Different Beverages on Microhardness of Single-Shade Universal Resin Composites

Objective: The aim of this study was to investigate the effects of different beverages on the microhardness values of single-shade universal resin composites. Materials and Methods: A total of 432 disk-shaped samples (10x2 mm) were prepared from eight single-shade universal resin composites produced by different manufacturers (Admira Fusion X-tra, Voco; Charisma Diamond One, Kulzer; Charisma Topaz One, Kulzer; Essentia Universal, GC; Omnichroma, Tokuyama; Optishade, Kerr; Vittra APS Unique, FGM; Zenchroma, President Dental). The samples were stored in distilled water (pH:7) as the control group and experimental groups were stored in coffee (pH:5), red wine (pH:3.5), coke (pH:2.5), multivitamin (pH:3), and green tea (pH:6) for a duration equivalent to 6 months of clinical use (37°C, 6 days). Vickers microhardness measurements were taken at the beginning (t₀), after thermal cycling (5-55°C, 5000 cycles), and following immersion in the beverages (t₁). The obtained data were analyzed using the Robust ANOVA and Bonferroni tests (p < 0.05). Results: There was statistically significant differences in microhardness values among tested single shade universal resin composites (p < 0.001). Admira Fusion X-tra exhibited the highest mean microhardness values (74.3). A statistically significant decrease in microhardness values was observed after immersion in all beverages (p < 0.001). Red wine caused the greatest reduction in microhardness among tested composites. A significant decrease in microhardness values was observed after immersion in all beverages. Interactions between composite type, beverage, and time are statistically significant. (p=0.001) Conclusion: Acidic beverages cause significant reductions in the microhardness values of single-shade universal resin composites. Neutral and slightly alkaline solutions showed less effect. Exposure to acidic beverages should be considered when selecting restorative materials.