To evaluate color changes to composite resins used to restore extracted teeth compared with composite discs after whitening with two agents: hydrogen peroxide (HP) and carbamide peroxide (CP). Ten human molars with class V vestibular and palatine cavity preparation obturated with Vita hybrid nanocomposite were hemisected to obtain 20 specimens assigned randomly to two groups: O1 and O2. Twenty composite discs were divided into two groups: D1 and D2. The groups O1 and D1 were treated with 16% CP, while groups =2 and D2 were treated with 37.5 % HP. Chromaticity coordinates L*, a* and b* were registered using a spectrophotometer. Statistically significant differences were found in O1 for L* and a*, in O2 for all three coordinates, and in D1 and D2 only for L*. Comparisons between groups found significant differences in ?Ee (end of treatment) between O1 and O2, between O2 and D2, and between D1 and O1. Both whitening agents produced significant decreases in the three-color components of composites used for dental restorations, while color changes to composite discs were limited to changes in luminosity. HP produced a greater color change to composite dental restorations than to composite discs.