Effect of food-simulating liquids and polishing times on the color stability of microhybrid and nanohybrid resin composites

The aim of this study was to evaluate the effect of food-simulating liquids and polishing times on the color stability of microhybrid and nanohybrid resin composite materials. One nanohybrid (Compofill) and one microhybrid (Dynamic plus) were used to prepare 120 samples each. Three polishing time subgroups were randomly assigned to each composite group. The polishing groups were treated with a one-step polishing system (Dimanto). Based on food-simulating liquids, the polishing groups were each separated into four subgroups (n = 10): ethanol, heptane, citric acid, and distilled water. Color change was evaluated by immersing the resin composites in liquids simulating food for 7 and 14 days. Three-way ANOVA was used for data analyses. When the color changes of the resin composites were compared, Compofill showed the lowest color change at baseline-7 days and baseline-14 days. In terms of food-simulating media, all times, the immersion in ethanol resulted in higher color variation compared to distilled water and citric acid while heptane showed an intermediate behavior. The nanohybrid composite showed less discoloration than the microhybrid composite. The discoloration of the nanohybrid resins after 7 and 14 days was below the clinically acceptable level. At all times, the increase in polishing time contributed to color stability.