Conversion and Shear Bond Strength of Experimental Self-Etching Adhesive

Objective: This study evaluates the relationship between the Degree of Conversion (DC) and Shear Bond Strength (SBS) of one experimental (EXP) two step self-etching bonding agent compare to three equivalent commercial products, Methods: The experimental formulation consisted of a Part-A and a Part-B system. Part-A was formulated using a newly developed dimer acid based phosphonate monomer, bisphenol-A-glycidyl dimethacrylate (Bis-GMA) and 2-hydroxyethyl methacrylate (HEMA) dissolved in ethanol. Part-B contained ethoxylate-bis-phenolA(Bis-EMA), dimer-dicarbamate-dimethacrylate (DDCDMA) and urethane-dimethacrylate (UDMA). Both parts were light activated with camphorquinone/ethyl-4-dimethylaminobenzoate. Three different commercial products were tested: Clearfill SE(Kuraray), AdheSE(Oratech) and Pro-Options(Ivoclar). DC (n=3) was assessed by near infrared spectroscopy in the adhesive(air dried) and bonding parts separately, as well as the combination adhesive/bonding(air dried). For the experimental formulation, DC was measured in the Part A and in the 1:1wt% mixture of Part-A and Part-B after air dry for 20s and in the Part-B without any previous treatment. Ultradent SBS tests were performed on dry dentin of human third molars after 24h water storage at 37^oC. N'Durance Universal Composite, from Septodont, was used with all adhesives in order to assure consistency in results. . All samples were prepared following the manufacturer's instructions. Statistical analysis of the data was performed using ANOVA and Student-Newman-Keuls test (p<0.001), Results: Results are shown in the table below. For each column, similar letters indicate that no significant differences were found.

Conclusion: Within the limitations of the current experiment, the results show that the DC as well as SBS differ significantly. A linear correlation was found between conversion and SBS.