Effect of universal primers and adhesive systems on bond strength of resin cements with and without 10-MDP to tribochemically silica-coated zirconia.

Although 10-MDP is widely recognized for its ability to enhance zirconia adhesion, commercially available MDP-containing systems differ substantially in formulation chemistry. This study investigated whether different 10-MDP-containing universal agents affect the bond strength of resin cements, with and without 10-MDP, when applied to tribochemically silica-coated zirconia surfaces. Zirconia blocks were randomly assigned to groups corresponding to different cementation protocols. Surface preparation involved tribochemical sandblasting with 30 µm silica-coated aluminum oxide particles for 15 s at 2.8 bar from a distance of 10 mm. After surface treatment, three universal primers and one adhesive were applied according to the manufacturer's instructions. Two resin cements, one containing 10-MDP and one without, were applied using a standardized cylindrical Teflon mold. Samples were stored in distilled water at 37 °C for 24 h, then subjected to micro-shear bond strength testing with a universal testing machine. Fracture types were analyzed using a stereomicroscope and examined with a scanning electron microscope (SEM). Bond strengths were evaluated using parametric (Student's t-test, one-way ANOVA) or non-parametric (Mann-Whitney U, Kruskal-Wallis) tests. Statistical significance was set at p < 0.05. Resin cement containing 10-MDP demonstrated significantly higher bond strength in the three universal agent groups compared to resin cement without 10-MDP (p < 0.05). In the Signum Zirconia Bond groups, no significant difference was observed between the two resin cements (p > 0.05). Zirconia bond strength is influenced by the presence of 10-MDP and the specific primer-cement combination used. These results indicate that commercially available MDP-containing systems are not necessarily interchangeable for zirconia bonding.