Characterization Of A New Dental Photocurable Resin Containing BMSOC And Nano-MgO

OBJECTIVE:This study was attempted to incorporate an antibacterial element,nano-magnesium?nano-MgO?,into a new low-shrinkage dental photocurable resin.The surface morphology,chemical composition,surface wettability and antibacterial property of the nano-MgO-incorporated resin after cured were investigated for elevating the new resin's antibacterial and physical-chemical property.Therefore,it might lay a theoretical foundation for the development of a new type of antibacterial low-shrinkage dental light curing composite resin.METHODS:In order to reduce the volumetric shrinkage further as a result of polymerization and keep the resin have good antibacterial activity,the three-component photo initiation system comprising CQ?camphoroquinone?,DMAEMA?N,N-dimethylaminoethyl methacrylate?and DPIHFP?diphenyliodonium hexafluorphosphate??1wt%/2wt%/2wt%?was adopted.Bismethylene spiroorthocarbonate expanding monomer?BMSOC?and3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate?epoxy?were mixed with Bisphenol-A diglycidyl methacrylate?Bis-GMA?as the matrix resin.Micron silica particles modified by?-?methacryloxypropy?methacryloxypropyl trimethoxy silane?KH570?and nano-magnesia?nano-MgO?particles in different ratios?0wt%,2wt%,4wt%,6wt%,8wt%?were used as fillers.According to the different ratios of nano-MgO,the specimens were divided into five groups:blank control group,A group,B group,C group and D group,respectively.The surface morphology of specimens was analyzed by Scanning electron microscope?SEM?.The chemical composition of specimens'surface was characterized by an X-ray energy spectrum analyzer?EDS?.Then the surface contact angle of experimental resins was measured by distilled water contact angle instrument.The antibacterial effect of experimental resins on the growth of Streptococcus mutans was determined by film contact test.The results of surface contact angle and antibacterial rate were expressed as mean and standard deviation and were analysed by one-way ANOVA using SPSS 23.0 software?a=0.05?.Results:1.According to the results of SEM,with the content of nano-MgO increased,more nano particles agglomerated.In the control group without added nano-MgO,the SiO₂particles particles were well dispersed on the whole.It shows that the presence of almost particles with the average size of 1?m,and the maximum diameter can up to3?m.The results of the energy spectrum analysis showed that the experimental resin contained carbon?C?,oxygen?O?,silicon?Si?and magnesium?Mg?elements,and the presence of SiO₂ and MgO components were initially confirmed.2.The surface contact angle of the experimental groups were higher than the clinical control group,with the difference being very significant?P<0.05?.The contact angle of C group and D group was higher than that of blank control group,with the difference being very significant?P<0.05?.The contact angle of the experimental group containing nano-MgO?8wt%?was lower than that of group C,but there was no statistical significance?P>0.05?.3.As the antibacterial component of nano-MgO increased,the antibacterial property of the resin gradually enhanced.The experimental D group containing nano-MgO?8wt%?showed the strongest antibacterial property,the antibacterial ratio of the resin can up to99%.Conclusions:1.This study successfully formulated a new dental light-curing composite resin containing nano-MgO and BMSOC,and the filler particles were evenly distributed in general.The agglomeration phenomenon between nano-particles increased with the increase of the content of nano-MgO particles,and the degree of agglomeration was related to the addition ratio of nano-MgO.2.When the nano-MgO content exceeded 6wt%,the surface wettability of the resin can be reduced.3.In this study,nano-MgO showed strong antibacterial activity against Streptococcus mutans.With the increase of nano-MgO content,the antibacterial property of the new composite resin gradually enhanced.