Influence of Light-Curing Units on Color Stability of Composite Resins After Aging

One of the most important problems with composite restorations is the loss of consistency between the composite and tooth color. The present study aimed to compare the color stability of two types of nanohybrid composites cured with different light-curing devices after aging.

In this study, the color stability of 40 disc-shaped specimens (10 mm in diameter and 2 mm in height) from two types of enamel and dentin nanohybrid composites (IPS Empress Direct, Ivoclar Vivadent) was investigated. A group of 10 samples of each composite was cured by light-emitting diode (LED) Bluephase device (Ivoclar, Vivadent) at 1200 mW/cm2 for 20 seconds, and another group of 10 specimens was cured by a quartz-tungsten-halogen (QTH) device (Coltolux 2.5, Colten, USA) at 600 mW/cm2 for 40 seconds. The initial color of the samples was determined by the Konica Minolta spectrophotometer (CS2000, USA), and then, the composite samples were subjected to an accelerated artificial aging (AAA) process in the QUV/SPRAY device. Then, the color of the samples was reassessed. Two-way analysis of variance (ANOVA) was used to compare the color changes in the study groups at a significance level of P=0.05.

The specimens cured by the LED device showed significantly lower color change compared to QTH (P=0.047). However, there was no significant difference in color stability between enamel and dentin composites cured by a fixed apparatus (P=0.474).

The curing of nanohybrid composites with LED devices causes lower color change compared to QTH.