Effect of Filler Porosity on Mechanical Properties of Dental Composite

Objectives: The purpose of this study was to investigate the effect of the filler type and porosity on the mechanical properties of new experimental dental composites, and compare these with the properties of a composite containing conventional glass filler. Methods: The experimental study new composites were prepared by mixing the silane-treated filler with the monomers. Experimental composites were divided into six groups according to their filler type, amount and porosity. The monomers were 70% BIS-GMA and 30% TEGDMA by weight for all groups.Comphorquinone and Amines were chosen as photo initiator system. Glass, Leucite ceramic and Lithium disilicate were prepared as different filler types. In order to create porosity on the fillers, Leucite fillers were treated with HF acid. Post curing was done for all groups. Degree of conversion of all composites was measured using FTIR spectroscopy. The diametral tensile strength (DTS), flexural strength and flexural modulus were measured and compared among groups. Results: Porosity of filler increased flexural strength significantly. The mean of flexural strength for composites containing porous fillers was 78 mpa in comparison with 53 mpa for control group and 43 mpa for conventional glass fillers. No significant differences were observed in DTS test among the groups. Flexural modulus increased using ceramic fillers. Type of the filler affected the DC of the composites and DC increased after post-curing. Conclusions: Flexural strength is one of the most significant properties of restorative dental materials. The higher flexural strength can be achieved by stronger and porous fillers.