Objective: To determine the effect of three bleaching agents on the enamel bond strength of a composite resin, after different artificial saliva storage times. Methods: 78 human premolars were mesiodistally sectioned to obtain two halves. The buccal and lingual surfaces were ground with 600-grit aluminum oxide abrasive paper and divided into a control group (n=12) and three experimental groups (n=48), according to the bleaching agents. The first group was bleached with Crest Professional Whitestrips (6,5% hydrogen peroxide), used 1 hour for 14 days. The second group was bleached with Opalescence Quick (35% carbamide peroxide), in three applications of 1h, with an interval of 7 days among them. The third group was bleached with Opalescence Xtra (35% hydrogen peroxide), in three applications of 16min, with an interval of 7 days among them. Specimens of control group was not bleached and were stored in artificial saliva for 14 days. After the bleaching treatments, the specimens of the experimental groups were divided into four groups (n=12), according to the storage time in artificial saliva (1 day, 1, 2 and 3 weeks). Bonds were formed with Scotchbond MP/Z-100 and shear bond test was carried out in an Instron Universal Testing Machine. The data were analyzed by two-way ANOVA, Tukey and Dunnett's tests (5%). Results: There was no significant difference among the bond strength of the three bleaching agents. Regarding to the post-bleaching time, the bond strength values obtained after three weeks were significant higher than the values obtained after one day, one and two weeks and were similar to those obtained for the control group. Conclusion: Bleaching with the agents tested significantly reduced the enamel bond strength of composite resin and after a lapse of three weeks, the values returned to that of the control group.

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