Effect of different light curing units and immersion media on roughness and color of a nanofill composite

Abstract Introduction The excessive consumption of soft drinks seems to change the properties of composites and may be associated with the light curing unit. Objective To evaluate changes in surface roughness (ΔR) and color (ΔE) of one composite polymerized with different light sources, immersed in distilled water or in Coca-Cola®. Methodology Sixty samples of nanofilled resin (FiltekMR Z350 XT, 3M) were distributed into following light curing units: a) quartz-tungsten-halogen (QTH) light; b) light emitting diode (LED) with polymer tip (LED 1) and c) LED with optic fiber tip (LED 2). Half of each group (n=10) was kept in water or immersed in Coca-Cola® for 20 minutes 2x/day during 14 days. Data were submitted to the Mann-Whitney and Kruskal-Wallis tests (p≤0.05). Result The ΔR was not significant among groups: in water: QTH = 0.006; LED 1 = 0.019; LED 2 = 0.010 (p=0.33); in soft drink: QTH = 0.021; LED 1= 0.011; LED 2 = 0.030 (p=0.86). The ΔE was not significant among light curing units: in water: QTH = 1.40; LED 1 = 1.80; LED 2 = 1.60 (p=0.31); in soft drink: QTH = 2.51; LED 1= 1.91; LED 2 = 2.61 (p=0.41), but was significant compared the immersion media (p=0.01), except for LED 1 (p=0.54). Conclusion The light curing lights did not interfere with the surface roughness and with color of nanofilled composite. Daily dives in soft drinks did not change smoothness, but the color changed to visually perceptible way, though clinically acceptable, according to the scientific literature parameters.