Effects of curing units and staining solutions on the color susceptibility of a microhybrid composite resin

To examine the effect of different light-curing units and staining solutions on a microhybrid composite resin. Two shades (A3 and B3) of a light-activated composite (Ecusit resin) were cured in polytetrafluoroethylene disk rings (45 each) using 3 different light-curing units: 1) a quartz–tungsten–halogen (QTH) unit, 2) a light-emitting diode (LED) unit, and 3) a plasma-arc curing (PAC) unit. Two beverages (coffee and tea) were used as staining solutions, and distilled water was used as a control. Evaluations were made after 1, 7, 15, and 30 days by means of reflectance spectrophotometry. Data were statistically analyzed using one-way analysis of variance, and post-hoc comparisons were made using Tukey’s test with a significance level of 5%. A Kruskal–Wallis multiple-comparison test was performed to evaluate ΔE∗ values among water, tea, and coffee immersion with 2 shades of the composite. Statistically significant color changes were observed between water and coffee, and tea and coffee for different time periods; whereas no difference was seen between water and tea in LED-cured A3 Ecusit resin specimens after either 1 or 15 days of immersion, those cured by PAC after 15 days of immersion, or in LED-cured B3 Ecusit resin specimens after 7 days. PAC-cured Ecusit resin specimens showed significantly higher discoloration than the other specimens. The staining solutions produced discoloration, while water caused the least changes.