Color changes induced by light curing of resin composites

Resumo

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/cm2
showed 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.