Eff ect of hydrogen peroxide in diff erent concentrations on the degree of bleaching and susceptibility to staining

Objective: The aim of this study was to evaluate the effi cacy of a bleaching material (hydrogen peroxide [HP]) in diff erent concentrations (20% and 35%) as well as the susceptibility to staining after the bleaching procedure. Materials and Methods: The root portions of 20 healthy bovine incisors were removed, and the crowns were sectioned, obtaining mesial and distal halves, totaling 40 specimens. The specimens were identifi ed as 1-20 (G1) for the mesial half and 21-40 (G2) for the distal half. The specimens of G1 were subjected to staining with coff ee and subsequently subjected to bleaching with HP 35% (specimens 1-10) and HP 20% (specimens 11-20). The specimens of G2 were stained with acai berry and later bleached with HP 35% (specimens 21-30) and HP 20% (specimens 31-40). After bleaching, the specimens were again subjected to staining with the same substances. The colorimetry system (CIELab) was carried out with a spectrophotometer at fi ve diff erent moments: Before the fi rst staining, after the fi rst staining and previously to the fi rst session of bleaching, previously to the second bleaching session, previous to the second staining, and fi nally after the second staining. Results: No diff erence was found between HP 35% and 20%, and both materials signifi cantly promoted bleaching. Conclusions: The acai solution resulted in more staining compared to the coff ee solution, before and after bleaching. No increase was observed in susceptibility to staining after bleaching of the bovine teeth.