Color Stability of a Microhybrid Resin Composite Polymerized with LED and QTH Light Curing Units

Discoloration of resin composites is a common reason for replacement of these restorations. The aim of this study was to eva-luate the influence of different light curing de-vices on color stability of a microhybrid resin composite. 80 disc-shaped speci-mens (8 mm in diameter, 2-mm height) were fabricated from filtek Z250 resin composite. Specimens were divided into 4 groups (n=20) and cured with LED (Bluephase C5, Valo) or QTH (Astralis7 with two different light intensity) light curing devices. Baseline color of each specimen was measured with a spectrophotometer according to the CIE (L*a*b*) color scale. (CIE L*a*b* is a color measurement system with dimension L for lightness and a and b for the color-opponent dimensions). Each subgroup (n=10) were immersed in tea or artificial saliva for 72h at 37°C. The color values of specimens were re-measured and the color change values (ΔE*ab) were calculated using One-Way ANOVA and Tukey test. A P value of <0.05 was considered significant. In groups immersed in tea, specimens cured with high power mode of Astralis7 (750mW/cm2), showed the statistically signifi-cant lowest color change. There was no statisti-cally significant difference between two types of Light Emitting Diode units. Conventional halogen light (QTH) with high power mode showed the maximum color stability in tea.