pH AND SOLVENT EFFECTS ON BONDING Bis-GMA RESIN ONTO TITANIUM

Objectives: The aim of this study was to evaluate the effect of pH and alcohol solvent of an activated silane solution on bonding a resin onto silica-coated titanium. Silanes are used as adhesion promoters for silica-coated metals, ceramics and composites. Methods: 3-methacryloyloxypropyltrimethoxysilane (MPS) was used between bis-phenol-A-glycidylmethacrylate (bisGMA) resin and silica-coated titanium surface. Two different MPS solutions were prepared by dissolving MPS in the mixture of 2-propanol or ethanol in de-ionized water (95vol%/5vol%). In both MPS solutions, the pH was adjusted at 4.5, 5.0, or 5.5, respectively. Six groups of MPS solutions were used for bonding. In every solution, BisGMA resin was light-cured onto silica-coated Ti surface (N=6/group). The shear bond strength was determined by measuring the load needed to break the bonding between bisGMA and Ti. A universal material testing machine (LRX, Lloyd Instruments, Fareham, UK) was utilized according to the ISO 10477 standard. The shear bond strength was calculated using NEXYGEN 2.0 software (Nexygen, Lloyd Instruments Ltd., Fareham, UK). Mean values for the shear bond strengths were analyzed with ANOVA. The statistical analysis was performed (Statistical Package for Social Science, SPSS inc., Chicago, USA). Results: The results showed no evident correlation between pH and the shear bond strength. Mean values for shear bond strengths were 10.23, 10.56, and 7.48 MPa (p<0.05) at pH 4.5, 5.0, and 5.5, respectively, when Ti-surface was silanized using MPS in 2-propanol. Using ethanol, the mean values for shear bond strengths were 6.46, 6.97, and 8.25 MPa (p<0.05) at pH 4.5, 5.0, and 5.5, respectively. Conclusion: According to this study, different pH values and solvents produced adequate shear bond strength values. The pH range of 4.5 to 5.5 is relevant to activate MPS solvents, in both alcohols.