Effect of 10-Methacryloyloxydecyl Dihydrogen Phosphate Concentrations in Primers on Bonding Resin Cements to Zirconia.

PURPOSE To investigate the effect of 10-methacryloyloxydecyl dihydrogen phosphate (MDP) concentration in primers on bonding of resin cements to zirconia. MATERIALS AND METHODS Highly translucent partially stabilized zirconia plates were bonded to stainless steel rods using one of 3 commercially available resin cements without adhesive functional monomers and without air-abrasion. Ten specimens of each resin cement group were pretreated with one of the primers containing 0.5, 1.0, 2.0, 3.0, 4.0, or 5.0 wt% of MDP dissolved in ethanol, or one of 3 commercial ceramic primers containing MDP and silane coupling agents. Untreated specimens were used as controls. The tensile bond strength was measured after 24 hours (TC0) and after thermal cycling at 4-60°C (TC3,500). Data were statistically analyzed using 1- or 2-way ANOVA and Tukey-Kramer post-hoc tests (α = 0.05). RESULTS The mean tensile bond strength in unpretreated group was significantly lower compared to that in pretreated groups with MDP-containing primers regardless of the resin cement used (p < 0.0001). The tensile bond strengths increased with an increase in MDP concentration from 0.5 wt% to 3.0 wt% or 4.0 wt%. Pretreated groups with 4.0-wt% MDP-containing primer showed significantly higher tensile bond strengths than pretreated groups with commercial ceramic primers regardless of the resin cement used and thermal cycling (p < 0.0001). CONCLUSION Primers containing 4.0-wt% MDP achieved higher bond strengths of resin cements to zirconia compared to commercial ceramic primers containing MDP and silane coupling agent. This article is protected by copyright. All rights reserved.