Physical and mechanical properties of flowable composite incorporated with nanohybrid silica synthesised from rice husk

This study aims to fabricate experimental flowable composites (FCs), by incorporating spherical nanohybrid silica as the filler and subsequently to evaluate their physical and mechanical properties in comparison to a commercial counterpart (Revolution Formula 2). The nanohybrid silica used in this study was synthesised from rice husk using sol-gel method and the dilution effect of Bis-GMA on the physical and mechanical properties of the experimental FCs was also investigated. Three experimental FCs (EF50B, EF45B and EF40B) were prepared by diluting the base monomer namely Bis-GMA to obtain the desired flowability. Surface roughness, surface morphology, Vickers hardness, compressive strength and compressive modulus of each group were determined. The data were statistically analysed using one-way ANOVA followed by Scheffe post hoc test. The surface roughness and Vickers hardness of the experimental FCs were comparable to Revolution Formula 2. Even though experimental FCs were inferior in compressive strength compared to Revolution Formula 2, they had passed the minimum requirement for compressive strength. The compressive modulus of experimental FCs was higher than Revolution Formula 2, but no statistically significant difference was detected except for EF50B. The dilution of the base monomer among the experimental FCs had no significant effect on their physical and mechanical strength. In conclusion, experimental FCs from rice husk had adequate physical and mechanical strength in comparison to the commercial counterpart rendering them a potential sustainable green-based product in dentistry. (C) 2019 The Authors. Published by Elsevier B.V.