ABSTRACT
Indirect resin composites are generally regarded to have better color stability than direct resin composites since they possess higher conversion degree. OBJECTIVE: The present study aimed at comparing the changes in color (ΔE) and color coordinates (ΔL, Δa and Δb) of one direct (Estelite Sigma: 16 shades) and 2 indirect resin composites (BelleGlass NG: 16 shades; Sinfony: 26 shades) after thermocycling. MATERIAL AND METHODS: Resins were packed into a mold and light cured; post-curing was performed on indirect resins. Changes in color and color coordinates of 1-mm-thick specimens were determined after 5,000 cycles of thermocycling on a spectrophotometer. RESULTS: ΔE values were in the range of 0.3 to 1.2 units for direct resins, and 0.3 to 1.5 units for indirect resins, which were clinically acceptable (ΔE<3.3). Based on t-test, ΔE values were not signifcantly different by the type of resins (p>0.05), while ΔL, Δa and Δb values were signifcantly different by the type of resins (p<0.05). For indirect resins, ΔE values were infuenced by the brand, shade group and shade designation based on three-way ANOVA (p<0.05). CONCLUSION: Direct and indirect resin composites showed similar color stability after 5,000 cycles of thermocycling; however, their changes in the color coordinates were different.