Study On Effect Of Aluminium Borate Whiskers-Silica Compound On The Reinforcement Of Dental Composite Resins

【Objectives】The aim of the study was to investigate the effect of sol-gel process of tetraethoxysilane (TEOS) on the modification of aluminium borate whiskers (ABw) and synthesize a kind of retentive filler compound-aluminium borate whiskers-SiO₂ particles, and study the effect of ABw-SiO₂ compound on properties of dental composite resins.【Materials and Methods】The ABw and nano-SiO₂ were mixed and modified by sol-gel process of TEOS, then thermally fused to form ABw-SiO₂ compound as inorganic fillers. The fillers were blended with dental resins by spatulation and the standard specimen (25mm×2mm×2mm) was fabricated. Flexural strength and flexural modulus were measured by a three-point flexural test. The chemical component and chemical bond of the fillers after modification were analyzed on a Fourier Transform Infrared Spectrometer (FTIR) and an Energy Spectrometer. Scanning Electron Microscope (SEM) was used to examine selected filler compound and fracture surfaces of specimens. The orthogonal experiment of L₉ (3)⁴, which had four factors including ABw:nano-SiO₂ mass ratio, the dosage of TEOS, the dosage of the silane coupling agent (γ-MPS) and the compound filler level, was designed to investigate effect of these factors on flexural properties of light-curing resin composites with ABw-SiO₂ compound. The unfilled resin was used as a negative control, while Z100 (shade A2) used as a positive control. Dual-curing composite resins were developed by using CQ, BPO and DHET as curing agents.【Results】Increasing the dosage of TEOS resulted in a significant increase in the measured flexural strength of dental composite resins containing ABw-SiO₂ compound (P<0.05). When the mass ratio of ABw:nano-SiO₂ was 3:1; the dosage of TEOS was 40%; the dosage of y-MPS was 2%, the filler level was 50%, the experimental light-curing dental composite got the optimal properties, with a flexural strength of 123.14±17.37MPa and a flexural modulus of 8.75±0.45GPa. The flexural strength of the optimal group was significantly higher than the unfilled resin group (P<0.05), but there was no significant difference in the flexural strength between the experimental composite and Z100 with shade A2 (P>0.05). Dual-curing dental composite reinforced with ABw-SiO₂ compound had a conversion degree of double bonds of 62.23%, significantly higher than light-curing group, but there was no significant difference on flexural properties between the two groups.【Conclusions】The flexural strength of dental composite resins with ABw-SiO₂ compound was significantly improved through the modification of ABw by sol-gel process of TEOS (P<0.05). ABw-SiO₂ compound could significantly improve flexural properties of light-curing dental composites (P<0.05). Dual-curing dental composite resins containing ABw-SiO₂ compound had a higher conversion degree of double bonds than light-curing composite.