The Effect of 15% Carbamide Peroxide Bleaching on the Shear Bond Strength of Composite to Enamel

Statement of problem: 

Carbamide peroxide bleaching has been implicated to adversely affect the bond strength of composite to enamel.

The purpose of this study was to evaluate the effect of carbamide peroxide bleaching on the shear bond strength of composite to bleached enamel bonded with a three step total etch system; Scotchbond Multipurpose(SBMP), and two simplified all-in-one systems; Prompt L-Pop (PLP) and i bond.

Seventy two human molar teeth were randomly assigned to three control and three experimental groups. The experimental groups were subjected to a %15 carbamide peroxide bleaching system. Twenty four hours later, all the control and experimental groups were bonded with cylinders of composite, using three dental bonding agents. After thermocycling, shear bond strengths were determined by a universal testing machine. The data were evaluated using one way ANOVA and Duncan tests (P<0.05).

The composite bond strengths of SBMP were 19.52±5.21 MPa to the unbleached and 7.95±4.16 MPa to the bleached enamel. For PLP, the unbleached enamel exhibited bond strengths of 9.66±2.89 MPa and, the bleached one showed a bond strength value of 5.39±0.66 MPa. For i-bond the composite bond strengths were 11.46±4.31 MPa to the unbleached and 6.41±2.01 MPa to the bleached enamel. There was a statistically significant difference between the shear bond strength of the control and experimental groups of each dental bonding agent (SBMP, P<0.001, PLP, P<0.001, i bond: P=0.002).

Bleaching with 15% carbamide peroxide used in this study reduced the bond strengths of the composite to the enamel bonded with a three step total etch and two simplified one step all-in-one dental bonding agents.