| Owing to convenient clinical manipulation, better esthetics, as well as desirablemechaical properties and biocompatibility, dental restorative resin composites are gradually usedinstead of conventional dental amalgam alloys and become the optimum material for teeth defectrestoration. With the widely application of resin composites from anterior restorations to posteriorrestorations, dentists’ and patients’ requirements of resin mechanical properties have beencontinuously improving. Therefore, how to further improve resin composites mechaical propertiesto make sure lasting repair in massive defect of posterior teeth is one of the key problems of resincomposites preparation and application. In addition, in order to improve restorative marginalintegrity, prevent secondary caries and reduce post-operative sensitivity, reducing polymerizationshrinkage also has been becoming a main challenge.Bisphenol A diglycidylether methacrylate (Bis-GMA)/triethylene glycol dimethacrylate(TEGDMA) system and was chosen as the organic matrix of the resin composites. The modifiedcommerical micro-SiO2and modified nano-SiO2were used as inorganic filles and explored theeffect of the two kinds of particles’ mass ratios on resin composites’ physical-mechanicalproperties. The results showed that when the mass ratios of the two kinds of particles were55:15,the resin composite had the best mechanical properties such as flexural strength (137.9±6.4MPa),flexural modulus (12.1±0.1GPa), compressive strength (323.5±8.3MPa) and Vicker’smicrohardness (75.5±0.9HV) which illustrated that packing density of spherical particlesreached optimum.To apply resin composites to posterior restorations more effectually, the mechnicalproperties need further improvement. The effect of inorganic fillers amount on resin properties were exprlored via fixing mass ratios of micro-SiO2and nano-SiO2(55:15, wt/wt). The resultsshowed that the mechanical properties of dental compsites were enhanced with increasedinorganic fillers content. When the mass fraction were more than75wt.%, the mechanicalproperties were gradually reduced. The resin composite with75wt.%silica particles (59wt.%microparticles and16wt.%nanoparticles) presented the optimum mechanical properties. Theflexural strength, flexural modulus, compressive strength and Vicker’s microhardness wereincreased by9%、14%、5%and3%, respectively. With the increase of inorganic fillers, thepolymerization shrinkage of resin composites decreased to2.73%. Howerer, the double bondconversion also decreased to54.4%. Based on above results, depth of cure and service behaviorof resin composites were also studied.To improve the double bond conversion and reduce polymerization shrinkage of resincomposites, POSS-Octavinyl substituted with typical polyhedral oligomeric silsesquioxanes wasused as filler. The eight vinyl functional group on the structure of nano-scale POSS-Octavinylsubstituted not only increased the number of activity crosslinking points but also improvedinterface interaction between inorganic phase and organic phase. In this text, resin compositeswith different amounts of POSS were prepared. The results revealed that resin compositesmechanical properties and double bond conversion improved with the increase of POSS amount.When the mass fraction of POSS was2wt.%, the mechanical properties were not changedsignificantly, but the double bond conversion increased by11%. Moreover, the addition of POSSobviously reduced polymerization shrinkage. When the mass fraction of POSS was10wt%, thepolymerization shrinkage was2.17%. For clinical application, depth of cure and service behaiourwere also explored.Considering the current situation of the development of domestic dental restorationcomposite resin, two kinds of optimized silica-based composite resin in the experiment and sevenkinds of clinical commonly used commercial resins were chosen to compare mechanicalpropertites, double bond conversion and depth of cure of resin composites. The research willbenefit further properties improvement of dental resin composites. |
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