Methods: : The samples were equally divided into 4 groups according to the materials and were shaped in cylinder using metal mold. The color of each sample was measured using a spectrophotometer and it was accelerated aging process using thermocycling for 10,000 cycles. Color change (ΔE) of each sample after thermocycling was measured and statistically analyzed, using One-Way ANOVA test and multiple comparison by Bonferroni method at a significant level of 0.05.
Results: All resin composites displayed color changes (ΔE) after thermocycling, There was a statistically significant difference among materials (p<0.001). The color changes Filtek Z350 XT ® and Ceram X duo®, Filtek Z350 XT ® and Tetric N Ceram®, Premise® and Ceram X duo®, Premise® and Tetric N Ceram® (P<0.001) were significantly different but no significant difference was observed between Filtek Z350 XT ® and Premise® , Ceram X duo® and Tetric N Ceram® (p=1.000).
Conclusions: Color change (ΔE) of Filtek Z350 XT ®and Premise® were different from those of Tetric N Ceram® and Ceram X duo®, and the color changes of all resin composites were not clinical acceptable.(ΔE>3.3).