Strong and bioactive dental resin composite containing poly(Bis-GMA) grafted hydroxyapatite whiskers and silica nanoparticles

Novel light-curable bioactive dental resin composite with enhanced physical and mechanical properties was prepared by combining poly(Bis-GMA)-grafted silanized hydroxyapatite whisker (PGSHW) with silanized silica (s-SiO2) nanoparticles in a bisphenol A glycidyl methacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) based dental resin matrix. The effect of PGSHW/s-SiO2 mass ratios on properties of the resin composites was investigated. The grafted poly(Bis-GMA) on silanized hydroxyapatite whisker (HW) optimized the PGSHW–matrix interfacial properties and improved the reinforcing efficiency of PGSHW in the composites. The addition of s-SiO2 effectively increased the degree of conversion and filler packing density of the resin composites. Mechanical test showed that PGSHW/s-SiO2 (mass ratio 2:4) hybrid fillers significantly improved flexural strength, flexural modulus, compressive strength and work of fracture of the resin composite, which were 39.1%, 61.1%, 50.1%, and 85.9% higher than those of the resin composite with single PGSHW filler, respectively. Besides, in vitro bioactivity test indicated that resin composites containing PGSHW had superior apatite forming ability. In conclusion, PGSHW/s-SiO2 (2:4) filled resin composite was developed with significantly improved mechanical properties and desirable bioactivity, a combination not available in current HA filled dental resin composite, which may be a promising material to reduce the occurrence of both restoration fracture and secondary caries.