The effect of five silane coupling agents on the bond strength of a luting cement to a silica-coated titanium.

The adhesive performance of five silane coupling agents in adhering resin composite cement (3M ESPE) to silica-coated titanium was evaluated. Titanium was tribochemically silica-coated by using the Rocatec system. Two volume percent solutions of 3-acryloyloxypropyltrimethoxysilane (Toray Dow Corning Silicone), N-[3-(trimethoxysilyl)propylethylenediamine] (Dow Corning), 3-mercaptopropyltrimethoxysilane (Toray Dow Corning Silicone) and bis-[3-(triethoxysilyl)propyl]polysulfide (Dow Corning) were prepared in 95 vol.% acidified ethanol and allowed to activate (hydrolyze). A pre-activated ca. 2 vol.% 3-methacryloyloxypropyltrimethoxysilane (ESPE Sil) was used as a control. The silanes were applied onto silica-coated titanium slides. Chemical activation reactions of the silanes were monitored by Fourier transform infrared spectrometry (Perkin-Elmer Spectrum One). RelyX ARC (3M ESPE) resin composite cement stubs were applied and photo-polymerized onto silica-coated titanium. The specimens were thermo-cycled (6000 cycles, 5-55 degrees C). Statistical analysis (ANOVA) showed that the highest shear bond strength (n=8 per group) value after thermocycling, 14.8 MPa (S.D. 3.8 MPa), was obtained with 2.0 vol.% 3-acryloyloxypropyltrimethoxysilane. Silanization and results with 3-methacryloyloxypropyltrimethoxysilane (control, ESPE Sil) did not statistically differ from 3-acryloyloxypropyltrimethoxysilane, 14.2 MPa (S.D. 5.8). The lowest shear bond strength was 7.5 (S.D. 1.9) MPa for N-[3-(trimethoxysilyl)propylethylenediamine] and 7.5 (S.D. 2.5) MPa for bis-[3-(triethoxysilyl)propyl]polysulfide. Both the type of silane (p<0.001) and storage conditions affected significantly the shear bond strength values (p<0.001). All silanes became activated according to the infrared spectroscopic analysis. Silanization with 3-acryloyloxypropyltrimethoxysilane or 3-mercaptopropyltrimethoxysilane might offer an alternative for bonding a luting cement to silica-coated titanium.