Influence of composite type and light irradiance on color stability after immersion in different beverages.

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- Filtek 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/cm ) or Radii-cal, SDI (RA-900 mW/cm ). 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 (T ) and after (T ) immersion. CIEDE2000 color difference (ΔE ) and whiteness index for dentistry (WI ) 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 WI values (T ) and lower ΔE values after immersion in WT, OJ, and RW. However, there was no effect of both factors on ΔE 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 WI values and better color stability. However, all samples immersed in colored beverages showed ΔE 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.