The effect of the novel silane system on the flexural properties of e-glass fiber-reinforced composites for dental use

Three functional silane coupling agents and their blends with a cross-linking silane for bonding continuous E-glass fibers to a bis-GMA resin system were evaluated by measuring the flexural strength and modulus. E-glass fiber specimens were randomly divided into two subgroups. The first subgroup was silanized with three functional silane coupling agents: 3-acryloxypropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane and 3-methacryloxypropyltrimethoxysilane. The second subgroup was silanized with these functional silanes blended with a cross-linker silane, 1,2-bis-(triethoxysilyl)ethane. Silanized fibers were embedded into an experimental bis-phenol-A-diglycidyldimethacrylate (bis-GMA)-based monomer system and light-polymerized to form fiber-reinforced composite (FRC) test specimens of size 2 mm × 2 mm × 25 mm (n = 6). The control group comprised FRCs with the original silane coupling agent coating on the E-glass fibers by the manufacturer. The storage conditions were: dry storage, 30 days and 6 months immersion in water (at 37°C). Flexural strengths and moduli of test specimens were measured and statistical analysis (ANOVA) was carried out. Fracture surfaces were imaged with a scanning electron microscope. The highest flexural strength for specimens stored in water for 6 months was obtained for the control sample with the original silane coating (399±91 MPa), and the lowest flexural strength value (309±138 MPa) was obtained using 3-isocyanatopropyltriethoxysilane. It is expected that silanization with other trialkoxysilanes than 3-methacryloxypropyltrimethoxysilane - or with some silane blends - may produce equal or slightly better flexural properties for fiber-reinforced composite using the experimental bis-GMA resin system.