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The effects of peroxide bleaching on composite to enamel bond strength
M V Dishman1, D A Covey, L W Baughan
1Department of General Practice, Medical College of Virginia, Virginia Commonwealth University, Richmond.
Objectives:
The objective of this in vitro study was to evaluate the effects of an in-office type of bleaching regimen on the composite to enamel bond.
Methods:
The enamel on forty extracted human teeth was subjected to a 25% hydrogen peroxide bleaching treatment. Ten additional unbleached specimens served as controls (Group A). The 40 bleached specimens were divided into four equal groups (Groups B-E). Composite cylinders were bonded to the prepared surfaces at various time intervals following bleaching. Group B was bonded immediately, Group C at 1 d, Group D at 1 wk, and Group E at 1 mon post-bleaching.
Results:
Mean shear bond strength values showed a significant decrease in bond strength for Group B. However, the bond strength returned to normal values after 1 d and remained normal for at least 1 mon. Scanning electron microscope examination showed an apparent decrease in the number of resin tags present in the enamel/composite interface for Group B compared with the other groups including controls.
Significance:
Polymerization inhibition of the resin bonding agent is the likely mechanism for the effects of the bleaching on bond strength.