A Study On The Composition And Application Of Dental Resin Composite With Improved Aging Resistance And Low Shrinkage

Dental resin composite primarily due to its exceptional aesthetics,manipulability,as well as physical and chemical properties,has been widely applied within the domain of dental restorations in general,and direct posterior restoration in particular.A clinical survey reported that dental resin composite spans less than a decade,mainly due to the adverse effects of fracture and secondary caries.Upon being positioned in an intricate oral condition,several factors,such as water immersion and long-term chewing stress,eventually lead to hydrolysis of restoration and degradation in performance.Additionally,shrinkage stress,which is induced by polymerization,has an impact on the adhesive interface between restoration and tooth tissue.Repetitive expansion and contraction due to temperature variation are bound to result in microleakage between restoration and dentine,thus promoting restoration failure and secondary caries.Despite the vast availability of commercial resin composites with low shrinkage,their aging resistance seems far from ideal.Therefore,in ascertaining satisfactory restoration,it is integral to enhance the comprehensive performance of resin composite through reduction in volume shrinkage,higher resistance towards hydrolysis and aging.At present,the prevalence of dimethacrylate chemical is high in dental resin composite,while inorganic fillers are widely varied.Polyhedral oligomeric silsesquioxane-dimethacrylate(POSS-MA),which refers to a type of organic-inorganic monomer,has an inner structure generated by silicon and oxide.The incorporation of POSS-MA enhances polymer strength.Substitution of conventional dimethacrylate monomer with macromolecular monomer decreases the amount of functional groups that react within a unit volume,hence minimizing volume shrinkage in resin.On top of that,owning to exceptional corrosion resistance and anti-permeability,glass flake has been widely applied to serve as waterproof in coating technology and coastal construction.Nevertheless,few studies have looked into the function of glass flake as a primary filler for packable dental resin composite in order to improve both aspects of mechanical properties and aging resistance in light of restoration.Chapter 1 presents a review of the development and the trend of visible light curing dental composite resins within recent years,as well as the organic and inorganic constituents currently applied within the dental composite resin,respectively.Chapter 2 elaborates the preparation of POSS-MA enhanced resin matrix.The optimal matrix formation had been achieved by examining physical and mechanical properties,thermal behavior,as well as water sorption and solution of matrix.The study outcomes displayed that 5wt% POSS-MA enhanced the strength of Bis-GMA/TEGDMA system,along with lower water sorption and solution.Chapter 3 depicts the modification of glass flake surface and compares the stability of water absorption between composites that composed of glass filler and Ba-Al-Si O2.The varied fractions of glass flakes/Ba-Al-Si O2 hybrid fillers had been combined with POSS-MA enhanced resin matrix to fabricate dental resin composite modified with glass filler.The effects of varying proportions of mixed fillers on resin composite properties had been assessed.The aging resistance of dental resin composite modified with glass filler was determined by comparing with other related commercial products.The outputs displayed that the dental resin composite modified with glass flakes had better aging and wear resistance.Chapter 4 illustrates the formulation of a new polyurethane dimethacrylate oligomer(BIMA)by using bisphenol A,isoflurone diisocyanate and hydroxyethyl methacrylate.A number of aspects,including mechanical property,polymerization and hydrolysis resistance of BIMA contained matrix,were analyzed to determine the optimal resin formulation.As a result,upon increment of BIMA up to 20wt%,shrinkage of resin matrix was minimized effectively,aside from generating enhanced hydrolysis resistance.Chapter 5 combines BIMA with high content of hybrid fillers to fabricate the final experimental dental resin composite.The amalgamation between BIMA and glass flakes/Ba-Al-Si O2 hybrid fillers decreased the volume shrinkage of composite resin and enhanced its aging resistance.Besides,this study has proven the ability of BIMA to effectively minimize shrinkage stress within the polymer network,which calls for further investigation within this research domain.Upon comprehensive consideration of mechanical properties,water absorption and solubility,degree of conversion,kinetics of polymerization,and aging resistance of dental resin composite,this study has successfully fabricated a novel dental resin composite with low shrinkage and enhanced aging resistance.This study offers fresh insight and fundamental basis for the development of new visible light cured composite resin,along with betterment of comprehensive properties.