Introduction: Enamel demineralization and white spot lesions associated with bleaching are some of the greatest challenges. Tooth pre-treatments with these agents on the enamel can therefore interfere with the bonding mechanism and the bond strength of brackets. Aim: The aim of this study was to compare the effect of CPP-ACP and fluoridated CPP-ACP on the shear bond strength of two different types of composites on bleached teeth. Methods: Seventy five sound human premolars were subjected to bleaching with an In-office whitening gel. After bleaching, the samples were randomly divided into six equal experimental groups: Group I and II (control), the brackets were bonded without any surface treatment; Group III and IV, the enamel surfaces were treated with CPP-ACP paste before bonding; Group V and VI, the teeth were treated with F-CPP-ACP paste before bonding. The samples in Groups I, III and IV bonded with Transbond XT composite and samples in Groups II, IIII and VI bonded with Transbond supreme composite. SEM photomicrographs of a tooth from each group were taken to observe the enamel surface.
Results: ANOVA comparison of six groups revealed statistically significant differences. There is a significant differences were found between the control groups and CPP-ACP-treated groups. However, highest Tensile SBS values was recorded for group III (13.61±4.69Mpa) and the lowest value was recorded for group II (7.62±3.68 Mpa). ARI scores were significantly different among the six groups (P < .001). Conclusion: CPP-ACP and CPP-ACP-F promoted the formation of hydroxyapatite and fluorapatite on weak bleached enamel surface.