Alternative Pretreatment Modalities with a Self‐Adhesive System to Promote Dentin/Alloy Shear Bond Strength

Purpose: The aim of this study was to evaluate alternative pretreatment modalities to enhance the dentin/alloy shear bond strength using a self‐etch adhesive system. Material and Methods: Ninety discs were fabricated and divided into three groups (n = 30). The discs of the first group were cast in gold palladium (Au‐Pd); those of the second group were cast in palladium silver alloy (Pd‐Ag); the discs of third group were cast in nickel chromium alloy (Ni‐Cr). Each group was further divided into three subgroups (n = 10) according to the dentin pretreatment used to lute the discs. Subgroup U (no pre‐treatment): Rely X Unicem resin cement. Subgroup GU: G‐Bond then Rely X Unicem. Subgroup ZU: Zinc‐Zeolite pretreatment then Rely X Unicem. Shear bond strength was determined using a compressive mode of force applied at the dentin/alloy interface using a monobevelled chisel‐shaped metallic rod. Data were collected and statistically analyzed to assess the effect of alloy type, pretreatment modality, and their interactions on the shear bond strength. Scanning electron microscopic examination (1000×) at the dentin/resin interface was performed. Two‐way ANOVA was used in testing significance for the effect of pretreatment, alloy, and their interaction. Duncan's post hoc test was used for pairwise comparison between the means when the ANOVA test was significant. The significance level was set at p≤ 0.05. Statistical analysis was performed with SPSS 15.0^®. Results: Regarding the pretreatment modality, the mean shear bond strength and 95% CI of subgroups ZU (18.00 MPa; 16.8 to 19.2) and GU (16.91 MPa; 15.4 to 18.4) were significantly higher than subgroup U (12.81 MPa; 11.4 to 14.2). Regarding the alloy type, the mean shear bond strength and 95% CI of Ni‐Cr groups (18.39 MPa; 16.9 to 19.9) were significantly higher than Au‐Pd (15.33 MPa; 13.8 to 16.8) and Pd‐Ag (13.99 MPa; 12.3 to 15.7). Conclusions: Pretreatment of dentin with G‐Bond and Zinc Zeolite improved the dentin/alloy shear bond strength. Base metal alloys provided superior bond strength values with any adhesive modality compared to noble alloys. Treatment of the dentin surface prior to the application of a self‐adhesive system is of great importance to enhancement of the dentin/alloy bond strength.