This study evaluated the effects of several low-concentration bleaching products on microtensile bond strength (µTBS) to enamel at different elapsed times after the bleaching treatment. One hundred and fifty bovine incisors were divided into five groups: No treatment, 10% carbamide peroxide (Opalescence), 10% hydrogen peroxide (Opalescence Treswhite Supreme), 3% carbamide peroxide plus lactoperoxidase (WhiteKin), or 3% carbamide peroxide plus 2.7% carbamide peroxide (Clysiden Kit Express). All treatments lasted 4 weeks. After bleaching treatment or non-treatment, teeth were restored immediately, at 1, 3, 7, or 14 days after bleaching and submitted to µTBS test. Data were analyzed by ANOVA and Tukey's test (p<0.05). For WhiteKin and Clysiden, µTBS to enamel was significantly reduced immediately, at 1, 3 and 7 days after bleaching. At 14 days after bleaching, similar µTBS values were obtained regardless of bleaching product. Therefore, while over-the-counter (OTC) products might affect bond strength to enamel, this effect was no longer observed after 14 days.
