The Study On EAM Based Resin Composite Applied To Fiber Post Cementation And Core Forming

In the clinic,the post-core was made to improve retention of crown and to restore tooth destroyed by decay and injury.The post-core materials keeped being refreshed with the development of dental materials and the application of allceramic restorati on technique.Since 90's,fiber reinforced post materials got popular because of excellent mechanical properties,biocompatibility and chemical affinity.Because fiber posts were made of epoxy resin reinforced by organic and inorganic fibers,resin luting cements became the most proper luting material,and also resin composite has been widely used as the core material for substant bonding between the resin base of fiber posts and dentin,suitable color and convenience in the clinic operation.Recently,resin composite for both cementation of fiber post and core forming has been put on into the market, which could simplify the process of core-making and improve the clinical efficiency.These materials could not only obtain good bonding strength between fiber posts and root canal,but also have excellent mechanical properties to bear the occlusion.Virtually,resin based luting cement is a kind of diluted resin composite, which has the similar composition to resin material for core-making.Resin composite is made of resin matrix,diluent,coupling agent,inorganic filler, initiation system,inhibitator and pigment.Resin base and diluent,which compose the resin composite,make it polymerable and determine its basic properties. Commercial resin composits in the market usually apply bis-phenol A glycidyl dimethacrylate(Bis-GMA) and urethane dimethacry late(UDMA) as resin matrix of the composite.And some inorganic filler such as silicon dioxide or titanium dioxide and initiator are added to enhance the mechanical strength of the resin. The ratio of fillers ranges from 20%to 85%according to different brands and indication of the resin.EAM resin is a kind of adjusted epoxy and methacrylic base resin,the previous researchers have proved this kind of resin had better mechanical properties and lowr water absorption and water solution,which seems to be a ideal resin matrix for composite material.The objection of this study was to develop a trial resin composite which had optical bonding and mechanical strength by the way of strength testing.The research included three parts,which was:1.the evaluation of the content of initiator in the EAM based resin.2.the evaluation of the content of inorganic fillers in the EAM based resin.3.the evaluation of mechanical strength of EAM based resin composite.The following results could be achieved from this study:1.In the standard enviroment,when the content of chemical initiator benzoperoxide in the EAM resin got into the range from 1.2%to 1.4%,its working time and curing time of polymer could meet the national standard in medicine YY 1042-2003.2.Tn the standard enviroment,when the content of photo initiator camphorquinone reached 0.2%,the curing depth of polymer could meet the national standard in medicine YY 1042-2003.3.On the basis of experiment above,we made comparisions among the polymerization conversion of chemical-curing,photo-curing and dual-curing resin at different moment after curing by the way of FTIR.The result showed that: polymerization conversion of dual-curing resin＞that of chemical-curing resin＞that of photo-curing resin;cured resin after 24h＞resin at the moment of curing.4.The bond strength of the resin cement was affected by the content of inorganic fillers in it.The bond strength of resin which contains 50%or 60% inorganic fillers was higher than that of resin in other groups,and there were no significant statistical difference between 50%and 60%groups.5.The content of inorganic fillers in the EAM based resin composite had an effect on its mechanical strength separately.When the content of the inorganic fillers got into the range from 62%to 64%,the mechanical properties of resin composite was highest,which were separately,flexural strength:110-112MPa, Diametral tensile strength:35 MPa,Compression strength:172-174 MPa, Surface hardness:46-48 MPa.