Dentin bonding of an etch-and-rinse adhesive using self- and light-cured composites

To evaluate the dentin shear bond strength (SBS) of a new two-step etch-and-rinse adhesive system (MPa Direct) using self- and light-cured composites.

The dentin of 160 bovine teeth was ground to 600 grit. Self- (Bisfil 2B) or light-cured (Filtek Supreme Plus) composite was bonded to dentin using MPa Direct, Adper Single Bond Plus, One-Step Plus, OptiBond Solo Plus, or Prime & Bond NT. For the light-cured composite, MPa Direct was used both with and without the HEMA/glutaraldehyde desensitizer (G5) supplied in the kit. For the self-cured composite, OptiBond Solo Plus and Prime & Bond NT were used with and without their respective self-cure activators. Those two adhesives and MPa Direct also were used with the self-cured composite after removal of the oxygen-inhibited layer from the adhesive. Following storage in water for 24 hours, shear bond strengths were determined using a universal testing machine. The data were subjected to factorial ANOVA and Tukey's test.

With the light-cured composite, the mean SBS of MPa Direct was 41.1 MPa. Use of G5 did not significantly affect mean SBS (35.7 MPa). Mean SBS of MPa Direct when used with the self-cured composite was significantly lower (16.6 MPa). However, removal of the oxygen-inhibited layer returned the bond strength (38.9 MPa) to the level obtained using light-cured composite. Both OptiBond Solo Plus and Prime & Bond NT had significantly lower bond strengths when used with the self-cured composite than with the light-cured composite, regardless of whether their self-cure activators were used. Removal of the oxygen-inhibited layer improved the bond strengths of these two adhesives, but the improvement was less than that observed for MPa Direct. Bond strengths of One-Step Plus and Adper Single Bond Plus were not affected by the type of composite resin used.