Bond Strength of Tissues Submitted to a Carbamide Peroxide Dentifrice

Objectives: Degradation products of carbamide peroxide may affect the polymerization of adhesive restorative systems, compromising the quality of the restorations. This paper aims to evaluate the shear bond strength of human enamel and dentin after the use of a carbamide peroxide bleaching dentifrice for 21 days. Methods: Enamel and dentin fragments were embedded, flattened and randomly divided into 3 groups (n=10): carbamide peroxide bleaching dentifrice - REM (Rembrandt Plus/ Den-Mat Corporation), fluoride dentifrice - CLO (Close Up with fluoride/ Gessy Lever) and immersion in artificial saliva as a control group (SAL). The application of the dentifrices was daily carried for 15 minutes with a slurry with water distilled in a ratio of 1:3 in weight for 21 days. Afterwards, the fragments were kept in artificial saliva solution. After the last application, specimens in micro hybrid composed resin (Z100ƒ} 3M) and adhesive system (Scotchbond Multi-Purpose) were constructed for the shear bond strength test that was performed in an universal machine with 0.5 mm/minute speed. Results: The ANOVA and Tukey test - for enamel - and the ANOVA and Dunn Method - for dentin - showed significant differences between REM and SAL, with higher values for REM. There were no differences between REM and CLO and between CLO and SAL for enamel and dentin. Conclusion: Carbamide peroxide bleaching dentifrices may increase the adhesive resistance of restorative systems, but no significant changes may be observed when compared to the use of a fluoride dentifrice.