In vitro evaluation of casein phosphopeptide-amorphous calcium phosphate effect on the shear bond strength of dental adhesives to enamel

BACKGROUND Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is applied for remineralization of early caries lesions or tooth sensitivity conditions and may affect subsequent resin bonding. This in vitro study investigated the effect of CPP-ACP on the shear bond strength of dental adhesives to enamel. MATERIALS AND METHODS Sixty extracted human molar teeth were selected and randomly divided into three groups and six subgroups. Buccal or lingual surfaces of teeth were prepared to create a flat enamel surface. Adhesives used were Tetric N-Bond, AdheSE and AdheSE One F. In three subgroups, before applying adhesives, enamel surfaces were treated with Tooth Mousse CPP-ACP for one hour, rinsed and stored in 37°C temperature with 100% humidity. This procedure was repeated for 5 days and then adhesives were applied and Tetric N-Ceram composite was adhered to the enamel. This procedure was also fulfilled for the other three subgroups without CPP-ACP treatment. After 24 hour water storage, samples were tested for shear bond strength test in a universal testing machine. Failure modes were determined by stereomicroscope. Data were analyzed by t-test and one-way analysis of variance with P < 0.05 as the level of significance. RESULTS In comparison between applied and non-applied CPP-ACP subgroups, there was no significant decrease in the shear bond strength to enamel only in Tetric N-Bond (P > 0.05). In non-applied CPP-ACP subgroups, there were statistically significant differences among all subgroups. Tetric N-Bond had the highest and AdheSE One F had the lowest shear bond strength. CONCLUSION CPP-ACP application reduces the shear bond strength of AdheSE and AdheSE One F to enamel but not Tetric N-Bond.