RESUMEN
OBJECTIVE: The aim of this study was to evaluate the color stability of two resin-based composites photo-activated by two light curing units (LCU) with different irradiances. MATERIALS AND METHODS: Hundred disc-shaped specimens (2-mm thick) of a nanofilled (FZ- FiltekTM Z350 XT, 3M ESPE) and a microhybrid (ED-Empress® Direct, Ivoclar Vivadent) composites were photo-activated with two LCU: Valo® Cordless, Ultradent (VA-1800 mW/cm2 ) or Radii-cal, SDI (RA-900 mW/cm2 ). Samples (n = 5) were immersed during 12 days in distilled water (WT), orange juice (OJ), red wine (RW), coffee (CF), or Brazilian tea (BT). CIELAB coordinates were obtained using a spectrophotometer (Easyshade 4.0, Vita Zahnfabrik) before (T0 ) and after (T1 ) immersion. CIEDE2000 color difference (ΔE00 ) and whiteness index for dentistry (WID ) were calculated. Data was analyzed by two-way ANOVA and Tukey's test (α = 0.05%). RESULTS: FZ light-activated by VA showed higher L* and WID values (T0 ) and lower ΔE00 values after immersion in WT, OJ, and RW. However, there was no effect of both factors on ΔE00 when samples were immersed in BT and CF. ED light-activated by RA showed significant higher C* values (p ≤ .05). CONCLUSIONS: The nanofilled composite photo-activated with higher irradiance showed greater L* and WID values and better color stability. However, all samples immersed in colored beverages showed ΔE00 values above the acceptability threshold. CLINICAL SIGNIFICANCE: Initial color of resin-based composites can change after immersion in staining beverages. However, the best color stability was obtained by the nanocomposite photo-activated by a light-curing unit of higher irradiance.