Color changes induced by light curing of resin composites

Abstract

Color changes that occur after the light-activation of resin composites should be understood. Objective: To evaluated the influence of light-curing devices on the color of resin composites immediately after light-activation and after one-week, at 37oC, into water storage. Material and methods: Three A2-shade composites (Z100, Z250, and Z350), and four light-curing devices (three halogens and one LED) were evaluated. Seventy-five cylindrical specimens were light-activated for 20s. CIE-Lab color was analyzed using a spectrophotometer. Color changes between uncured and immediately light-activated materials (∆E1), and between immediately light-activated and one-week-37˚Cwater-stored materials (∆E2) were obtained. Data were evaluated by two-way Anova, followed by Tukey test (α = 0.05). Results: For ∆E1, composites (p = 0.0008), lights (p = 0.015), and the interaction (p = 0.017) were significant. Z100 showed the smallest value (3.08 ± 1.73). The halogen 210 mW/cm2 device showed the smallest ∆E1 (3.09 ± 1.25), while the LED 200mW/cm2 showed the highest value (4.94 ± 2.37). For ∆E2, composites (p = 0.00016), lights (p < 0.0001), and the interaction effect (p = 0.0002) were significant. Z350 showed the smallest value (2.24 ± 1.17). The halogen 400mW/cm2 device showed the smallest ∆E2 (2.15 ± 2.15), while the halogen device 525mW/cm2showed the highest value (4.45 ± 2.15). Conclusion: The color of resin composites change significantly from the uncured to the cured and water-aged phases.