Preparation and characterization of silica based nanocluster dental nanocomposite materials

The amount and type of fillers have a significant influence on the properties of dental resin composites. In this study, silica nanoclusters were synthesized and their effect on the properties of UDMA / BisGMA / TEGDMA based dental composites were evaluated. Nanoclusters were prepared by polymerization of surface modified commercial silica nanoparticles (Aerosil OX50 and Aerosil R709) with TEGDMA monomer. The composite obtained at the end of the polymerization was pulverized with a ball mill and sieved with a micro sieve (75 µm), and the nanoclusters obtained were then used as a filler to prepare dental composites. The composites were prepared using UDMA/BisGMA/TEGDMA (55:25:20 weight ratio) monomers as matrix system with varying proportions of filler loading (between 40 wt.% and 70 wt.%). The prepared clusters and composites were characterized by SEM, TGA and FTIR. The results have shown that that the composites obtained by doping synthesized silica nanoclusters improve water absorption, solubility, and flexural strength. In addition, increase nanocluster filler load caused a decrease in polymerization shrinkage and increase in flexural strength. When nanoclusters and nanoparticles were used as filler material, the increase in filler load caused a decrease in both water absorption and solubility values of the composites. The flexural strength, on the other hand, increased until a certain critical filling load was reached; then it started to decrease. At 50% filler load, composites filled with nanoclusters outperformed composites filled with nanoparticles in flexural strength. When nanoparticles and nanoclusters were used together as filling material, it was found that the obtained composite had the lowest polymerization shrinkage of 2,2% and the highest bending strength of 113,91 MPa.