Laboratory evaluation of one-component enamel/dentin bonding agents

To evaluate the bonding efficacy of five commercial and one experimental one-component enamel/dentin adhesives.

The adhesives One-Step (BOS), Primabond (PAB), Prime & Bond 2.0 (PB2), Solist (SOL), Tenure Quik (TEQ), and an experimental compound (EXP) were investigated. The adhesives were used to bond a hybrid-type resin composite to enamel and dentin. Shear bond strength (SBS) to human teeth was determined after 24-hour storage in water. The marginal performance was evaluated on restorations in 3.5 mm wide cylindrical dentin cavities as the maximum gap width found 15 minutes after light activation. The hybrid layer thicknesses at the cavity margin were measured by light microscopy.

Mean SBSs to enamel were between 23 and 35 MPa, those to dentin between 3.5 and 25 MPa. BOS and EXP showed the highest bond strengths to dentin and consistently gap-free restorations. PB2 mediated significantly lower SBS to dentin; only three of the six restorations were gap-free. SOL exhibited poor marginal quality (mean MGW 7.5 microns) despite 15 MPa dentin bond strength. PAB and TEQ demonstrated very low SBS to dentin. None of the restorations with these products was gap-free. All adhesives produced hybrid layers between 2 and 10 microns thick, as a coupling zone between dentin and restoration. Adhesives with the essential components of wetting monomer, well-polymerizing dimethacrylate, and acetone as the water-chasing solvent, performed very well when used with a moist bonding technique.