Effect of long-chain silane on mechanical properties of experimental resin composites

Abstract

Abstract Purpose To investigate mechanical properties of experimental resin composites contain 8-methacryloxyoctyltrimethoxysilane (MOS) and a commonly used silane, 3-methacryloxypropyltrimethoxysilane (MPS). Materials and methods MOS and MPS were hydrolysed in 95vol% ethanol solution at pH 4 for 1h before silanisation of SiO2-based bioactive glass powder fillers (Ø 1.0µm, Schott, Germany) at 3, 6, 9 and 12wt% of silane. After drying in a vacuum oven (80°C, 5kPa, 2h) they were mixed with a monomer mixture of urethane dimethacrylate and triethylene glycol dimethacrylate in a 70:30 weight ratio, camphorquinone 0.7wt% and 2-(dimethylamino)ethyl methacrylate 0.7wt% to produce eight experimental groups of resin composites with a filler load of 72.7wt%. After photopolymerisation for 25 min and post-curing at room temperature (24h), uniform rectangular beams were cut out for the three-point bending test (2mm × 2mm × 25mm, n = 8). The surface Vickers microhardness (VHN) test (press-load 2.94N for 10s, n = 6; Duramin 5, Struers) was performed before observation under 3-D optical microscopy. Statistical analysis was performed using ANOVA followed by the Tukey post hoc test (p < 0.05). Results ANOVA revealed that both silane type and concentration significantly affected flexural modulus (p < 0.001), flexural strength (p = 0.001) and microhardness (p < 0.001). Resin composites containing MOS exhibited lower flexural modulus but higher strength at a lower concentration than MPS. MOS resin composites exhibited lower surface microhardness than MPS with the corresponding silane content. Conclusion Long chain silane may confer better mechanical properties, particularly a higher flexural strength to experimental composites compared with the current gold standard of MPS at a suitable concentration.