Bond strength between four luting systems and enamel modified with phosphoric acid.

The purpose of this study was to investigate the effect of phosphoric acid etching on the bond strength between enamel and three luting materials employing self-etching primer (PanaviaF2.0, Linkmax, and Multibond). A luting material without self-etching primer (Super-Bond) was used as a control. Two etching agents (K-etchant and Red Activator) were prepared. The surfaces of bovine enamel were ground, etched with either K-etchant or Red Activator, and then bonded to a stainless steel rod. Tensile bond strengths were determined following 24-hour immersion in water. Without etching, all of the luting materials showed the same statistical bond strength. When K-etchant was applied, the bond strengths of PanaviaF2.0, Linkmax, Multibond, and Super-Bond were significantly greater than that of non-etched control. No significant differences were found between K-etchant and Red Activator. Strongest bonds were obtained for Super-Bond in conjunction with K-etchant (23.6 +/- 6.3 MPa) or Red Activator (21.0 +/- 6.5 MPa), whereby the values were statistically comparable.