Shear bond strength between resin and zirconia with two different silane blends

Abstract

Objective. To study in vitro the effect of two cross-linking silanes, bis-1,2-(triethoxysilyl)ethane and bis[3-(trimethoxysilyl)propyl]amine, blended with an organofunctional silane coupling agent, (3-acryloxypropyl)trimethoxysilane, on the shear bond strength between resin-composite cement and silicatized zirconia after dry storage and thermocycling. Materials and methods. Six tested groups of 90 samples of yttria stabilized zirconia were used for sample preparation. The surfaces of the zirconia were silica-coated. 3M ESPE Sil silane was used as a control. Solutions of (3-acryloxypropyl)trimethoxysilane with cross-linking silanes bis-1,2-(triethoxysilyl)ethane and bis[3-(trimethoxysilyl)propyl]amine were applied onto the surface of silicatized zirconia. 3M ESPE RelyX resin-composite cement was bonded onto the silicatized and silanized zirconia surface and light-cured. Three groups were tested under dry condition and the other three groups were tested for thermocycling. The shear bond strength was measured using a materials testing instrument. Group mean shear bond strengths were analysed by ANOVA at a significant level of p < 0.05. The zirconia surface composition was analysed by X-ray Photoelectron Spectroscopy. Results. The highest shear bond strength was 11.8 ± 3.5 MPa for (3-acryloxypropyl)trimethoxysilane blended with bis-1,2-(triethoxysilyl)ethane (dry storage). There was a significant difference between mean shear bond strength values for (3-acryloxypropyl)trimethoxysilane blended with two cross-linking silanes, bis-1,2-(triethoxysilyl)ethane and bis[3-(trimethoxysilyl)propyl]amine, after thermocycling (p < 3.9 × 10⁻⁸). Various surface treatments of zirconia influenced the surface roughness (p < 4.6 × 10⁻⁶). The chemical composition analysis showed there was an increase in silicon and oxygen content after sandblasting. Conclusions. The results suggest that the combination of functional (3-acryloxypropyl)trimethoxysilane with cross-linking bis[3-(trimethoxysilyl)propyl]amine showed superior hydrolytic stability than with bis-1,2-(triethoxysilyl)ethane.