THE EFFECTS OF PEROXIDE BLEACHING ON COMPOSITE TO ENAMEL BOND STRENGTH

Objectives. The objective of this in vitro study was to evaluate the e ffects of an in-office type of bleaching regimen on the composite to e namel bond. Methods. The enamel on forty extracted human teeth was sub jected to a 25% hydrogen peroxide bleaching treatment. Ten additional unbleached specimens served as controls (Group A). The 40 bleached spe cimens were divided into four equal groups (Groups B-E). Composite cyl inders were bonded to the prepared surfaces at various time intervals following bleaching. Group B was bonded immediately, Group C at 1 d, G roup D at 1 wk, and Group E at 1 mon post-bleaching. Results. Mean she ar bond strength values showed a significant decrease in bond strength for Group B. However, the bond strength returned to normal values aft er 1 d and remained normal for at least 1 mon. Scanning electron micro scope examination showed an apparent decrease in the number of resin t ags present in the enamel/composite interface for Group B compared wit h the other groups including controls. Significance. Polymerization in hibition of the resin bonding agent is the likely mechanism for the ef fects of the bleaching on bond strength.