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Gypsum has been recognized as acceptable for human consumption as a dietary source of calcium. During contact with teeth, it releases Ca2+ ions needed for remineralization of tooth tissue, and therefore based on the concept of remineralization, gypsum may be a strategic additive for dental restorative materials. Hence, the objective of this study was to develop and characterize a novel dental material reinforced with different weight fraction of micro sized gypsum filler particle. A novel composite material was fabricated using conventional resin matrix consisting of Bisphenol‐A glycidyl methacrylate (Bis‐GMA), tri‐ethylene glycol dimethacrylate (TEGDMA), camphorquinone (CQ) and ethyl 4 dimethyl amino benzoate (EDMAB). Four different compositions were prepared by reinforcing different weight percentage (0–3 wt%) of silane functionalized micro sized gypsum particle. Fourier Transformed Infrared spectroscopy (FT‐IR), Transmission Electron Microscope (TEM) and Thermogravimetric Analysis (TGA) of silane treated filler were used to study the coupling phenomena between filler and resin. Polymerization shrinkage of composites was evaluated using specific gravity method. The Dynamic Mechanical Analysis (DMA) result revealed that the Glass transition temperature was found to be decreased by 15°C compared to unfilled composite. It was also found that the 2 wt% gypsum content recorded the highest value of storage modulus. Simultaneous Thermal Analysis (STA) result revealed that 2 wt% gypsum filled dental composite exhibited maximum thermal stability. The novel dental material exhibited better physical, optical, mechanical, thermal properties and lowest polymerization shrinkage with maximum conversion. POLYM. COMPOS., 38:404–415, 2017. © 2015 Society of Plastics Engineers

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The aim of this study was to analyze the effect of adding different weight percentages of nanoalumina particles on mechanical properties of resin-based dental composite materials. The composite specimens were prepared by dispersion of different percentage weight fractions (0 wt%, 1 wt%, 2 wt% and 3 wt%) of silane-modified nanoalumina filler in a monomer system containing 50% bisphenol-A glycidyl methacrylate, 49% tri-ethylene glycol dimethacrylate, 0.2% Camphorquinone and 0.8% Ethyl 4-dimethylaminobenzoate. The filler particle before and after silane treatment was characterized using Fourier-transform infrared spectroscopy and transmission electron microscopy. The presence of C ¼ O bond and Si-O-Si linkage between the monomer and filler was clearly indicated. Mechanical behavior of the lightcured samples was evaluated using compressive strength test, three-point flexural strength test, Vicker Micro hardness tests, dynamic mechanical analysis and simultaneous thermal analysis. The results indicated a more than 16% increase in the compressive strength in the samples containing nanoalumina filler particles. Vickers hardness of composite was increased by approximately 28% with respect to unfilled composite. The flexural modulus of composite mixed with alumina nanoparticles was increased from 1.7 to 5.1 GPa, while the values of composite were slightly decreased from 84.5 to 59.5 MPa. The dynamic mechanical analysis result revealed that the glass transition temperature was found to be increased by 30 C compared to unfilled composite. It was also found that the 1 wt% nanoalumina content recorded the highest value of storage modulus. The weight loss profile and thermal stability from thermogravimetric analysis results revealed that the composite filled with 2 wt% nanoalumina content exhibited maximum thermal stability.

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The main challenges encountered in the development of dental composites are to formulate the composites with minimum polymerization shrinkage without sacrificing degree of conversion. To overcome this problem, various fillers and composite materials have been proposed till date, but the analysis was limited. Hence, our main objective of this study was to investigate the polymerization shrinkage and mechanical behavior of resin-based dental composite by means of adding different weight fraction of silane-modified nanosilica particles. The dental composite consisting of a monomer system (50 wt.% bisphenol-A glycidyl methacrylate (Bis-GMA), 49 wt.% tri-ethylene glycol dimethacrylate (TEGDMA), 0.2 wt.-% Camphorquinone and 0.8 wt.-% Ethyl 4 dimethyl amino benzoate) was filled with different weight percentage of silane-modified nanosilica particles. Fourier transform infrared (FTIR) spectroscopy and transmission electron microscope (TEM) analysis of modified nanosilica particles clearly indicated the presence of C ¼ O bond of carbonyl group and stable siloxane linkage between the monomer and filler particle. The mechanical results indicated that the composite with 3 wt.% nanosilica particle exhibited maximum depth of cure (4.2 mm) and the lowest polymerization shrinkage (1.53%). However, unfilled dental composite exhibited maximum compression strength (464 MPa) which was approximately 55% more than the compressive strength of filled composite. Finally, Dynamic mechanical analysis (DMA) results revealed that 1 wt.-% nanosilica content recorded the highest value of storage modulus. The proposed dental material exhibited better mechanical properties and lowest polymerization shrinkage with maximum conversion.