Fundamental Research Of Light Curing Composite Resin Incorporating A Novel Monovinyl Acrylates Monomer

Composite resins are widely used in dental clinical applications, because of its beautiful color, easy to operate and good mechanical properties. However, polymerization shrinkage within the composite readily builds up once the polymerization exceeding the gel point conversion.Polymerization shrinkage at the tooth composite interface have the potential to cause adhesive failure,initiating microleakage and recurrent caries,which is one of the largest causes of short service time of current resin composites.Polymerization shrinkage may lead to the deformation of the cusp,second caries,repair failed or even enamel microcracks in clinically.Therefore, the composite resins of low polymerization shrinkage and stress have gained considerable attention from researchers as potentially being one of the urgent problems of composite restorations.The main ingredient of the traditional composite resin is Bis- GMA. The volumetric shrinkage of the composite resins during polymerization arises from the wan der Waals distance between the monomer molecules is replaced by a convalent bond during polymerization,and the intermolecular distance between the polymer chains becomes smaller than that between the monomers. The Bis- GMA is very thick and not conducive to the addition of the filler.Because of TEGDMA increasing the content of carbon carbon double bond,the composite resin of the polymerization shrinkage is increasing. At present, the research mainly focuses on the traditional composite resin research and the development of new type composite resin.The new type of liquid crystal monomer synthesis is expensive and limits the clinical application. The main ingredient of the most commercial dental resin is still Bis – GMA. Bis – GMA decides the main performance of the composite resin. If Bis- GMA were modified,the filler and the initiator must carry on the corresponding modification.Therefore,its cost is low so we modified the diluent of TEGDMA.According to the above problem,the research has prepared a series of the vinyl acrylic resin monomer with secondary functional groups.Then,we join them into the composite resin to reduce the viscosity of the Bis – GMA and improve overall performance of the resin.In the study,the new monovinyl acrylates monomer(BOCNA) was incorporated into traditional composite resin as an experimental group(Ep).The composite resin used TEGDMA served as a control group 1(Co1) in addition to select four composite resin P90,Tantric N-Ceram,Neofil,Gradia Dierct as a control group 2-5(Co2-5). We try to explore the new monovinyl acrylates monomer as diluent used in dental materials effecting Function Modification and to evaluate the new monovinyl acrylates monomer effecting on the polymerization shrinkage,polymerization shrinkage stress, mechanical properties, sorption/solubility and the effectiveness of microleakage preservation.The study was divided into 5 parts.At first,the new monovinyl acrylates monomer(BOCNA) effects on the compressive strength,diametral tensile strength,flexural strength and microhardness were obtained using universal test machine by ISO standard. The new monovinyl acrylates monomer(BOCNA) effects on the sorption/solubility was determined by weight method.Then,the new monovinyl acrylates monomer(BOCNA) effects on the polymrization shrinkage was determined by Micro-CT image reconstruction technique.The new monovinyl acrylates monomer(BOCNA) effects on the polymrization stress was determined by a sensor.Finally,we establish model estuary to assessment of microleakage determining by dye penetration test.The results showed as follows: The compressive strength,diametral tensile strength,flexural strength and microhardness of the new composite resin were 107.72(Mpa), 254.15(Mpa),29.85(Mpa),66.45(Mpa),were showed negative influence of the other five group. The new composite resin do not affect the sorption/solubility and its value were 20.95(μg/ mm3)and 2.99(μg/ mm3).The polymerization shrinkage and polymerization shrinkage stress of the new composite resin were 1.83(Mpa)和 2.67(Mpa) lower than the traditional composite resin.The new composite resin showed negative influence of the other three group except P90. The new composite resin has beneficial influence of preventing microleakage and improving the durability of the restoration.Overall, the ability of the new monovinyl acrylates monomer(BOCNA) to reduce polymerization volumetric shrinkage without a proportional reduction in mechanical properties and sorption/solubility provides a basis for improvement of low-shrinkage composite resins, and an effective way to prevent microleakage and enhance the perdurable stability of the bonding interface.The material has its value on clinical application.