摘要：OBJECTIVE: The aim of this study was to evaluate the effect of thermocycling on the color stability of three indirect composite resins. MATERIALS AND METHOD: In this study, three indirect composite resins: Artglass, Solidex and Signum were tested. Ten specimens (10 mm diameter and 2 mm depth) were prepared from each composite material and were polymerized at both sides for 180 s at 320-500 nm using a xenon stroboscopic light curing unit. The specimens were then subjected to polishing procedures using medium, fine and super fine grit aluminum oxide discs. After initial measurements were made with a colorimeter according to CIELAB system, specimens were subjected to 5000 thermocycles between 5 oC and 55 oC with a dwell time of 25 s in each bath and with a transfer time of 10 s between baths. After the thermocycling procedure, colors of the specimens were re-measured and color changes (∆E) were determined. RESULTS: The color change for all composite resin materials were above the clinically acceptable limit (∆E>3.3). The greatest color change was found for Solidex composite resin samples (∆E=6.87); this value was significantly different from those for Artglass (∆E=4.87) and Signum (∆E=5.27) samples (p<0.05). Color change values for the Artglass and Signum samples were not statistically different from each other (p>0.05). CONCLUSION: After thermocycling, the color changes of all the tested indirect composites were above the clinically accepted values. In clinical application, these results should be considered during composite resin selection, and teeth restored with indirect resin should be controlled more frequently.
