Objectives: Engineered silane blends may enhance significantly bonding. Silica-coated zirconia needs silanization when cementing with an organophosphate-resin-composite. Four experimental blends, a functional silane and a cross-linking silane (Novel Silane System), were evaluated in promoting adhesion of resin-composite to zirconia.
Methods: Zirconia (Procera, Nobel-Biocare) specimens were silica-coated (Rocatec, 3M ESPE) and silanized with the experimental silane blends. Blends consisted of 1.0 vol% of 3-acryloyloxypropyltrimethoxysilane (‘ACPS', Toray Dow Corning), glycidoxypropyltrimethoxysilane (‘GPS', Dow Corning), 3-isocyanatopropyltriethoxysilane (‘ICS', ABCR) or 3-styrylethyltrimethoxysilane (‘STYRX', ABCR) monomers in 95.0%/5.0% ethanol/water, with pH of 4.5. A cross-linking silane monomer bis-1,2-(triethoxysilyl)ethane (‘BTSE', Gelest) was added to each of the solutions, corresponding a final 2.0 vol% of silane. Fourier transformation Infra-Red (FTIR) spectroscopy was applied to monitor the chemical activation of the experimental silane solutions. RelyX Ceramic Primer (3M ESPE) was used as control. RelyX Unicem (3M ESPE) organophosphate-resin-composite was photo-polymerized as stubs (n = 14/group) onto zirconia. The shear bond strength was measured after dry storage (24 h) or thermo-cycling (5.0-55.0°C, 6000 cycles).
Results: FT-IR analysis suggested that silane blends were activated within 1 h. All shear bond strength values were enhanced during thermo-cycling: statistical analysis (ANOVA) showed that the highest shear bond strength, 14.9 MPa (SD 4.2 MPa), was obtained using glycidoxypropyltrimethoxysilane + bis-1,2-(triethoxysilyl)ethane. The lowest shear bond strength was 6.5 MPa (SD 2.6 MPa) with the control. Failure mode was 50% cohesive.
Silane | Shear bond strength (SD)/MPa (dry storage) | Shear bond strength (SD)/MPa (thermo-cycling) |
Control | 4.5 (1.3) | 6.5 (2.6) |
ACPS+BTSE | 6.9 (2.7) | 13.5 (4.4) |
GPS+BTSE | 11.0 (2.2) | 14.9 (4.2) |
ICS+BTSE | 9.1 (2.1) | 9.7 (6.3) |
STYRX+BTSE | 6.3 (1.8) | 14.5 (3.0) |
The storage conditions (p < 0.001) and type of silane (p < 0.001) affected significantly the shear bond strength.
Conclusions: Silanization with novel silane system yielded significantly higher shear bond strengths than the ready-to-use silane.