Objective: To assess the influence of dental bleaching on the susceptibility of developing carieslike lesions. Method and Materials: Enamel slabs obtained from recently extracted human third molars were submitted to different bleaching techniques: at-home, with 10% and 16% carbamide peroxide (G1 and G2, respectively; Whiteness Perfect); and in-office, with 37% carbamide peroxide (G3; Whiteness Super) and 35% hydrogen peroxide (G4; Whiteness HP), activated by light-emitting diode and laser. The control groups G5 and G6 were not bleached. Afterward, all specimens, with the exception of G6, were exposed to a highly cariogenic challenge by means of pH cycling. G6 served as the control for the artificial caries development methodology. Assessment of the enamel carieslike lesions was made visually by 3 independent examiners, who attributed scores representing the severity of white spot lesions (0 to 3). Statistical analysis was performed with the Kruskal-Wallis (P ¡Ü .001) and multiple paired comparison tests. Results: Interrater reliability was expressed in a range of 0.70 to 0.82 kappa values. The median scores per group were as follows: G1 and G2 = 1; G3, G4, and G5 = 2; and G6 = 0. Conclusion: Home bleaching reduced the susceptibility to dental caries, while in-office bleaching did not influence the development of caries lesions. (Quintessence Int 2007;38:614.e404¨C409)

Key words: demineralization, dental caries, enamel, in vitro, remineralization, tooth bleaching