Preparation And Properties Of Novel Bioactive Glass Modified Composite Resin

OBJECTIVE: Secondary caries is the most important reason for the failure of composite resin filling,but up to date,there is still no real effective solution.Bioactive glass has been proven to have good antibacterial and remineralization properties,but the effects of bioactive glass modified composite resin on the antibacterial properties,dentin mineralization properties and biosafety is still unclear.Therefore,this study developed a new type of composite resin with both antibacterial and mineral-promoting properties by incorporating different proportions of bioactive glass,and clarified the regulatory effect underlying mechanism of bioactive glass on mechanical properties,antibacterial properties,mineralization properties and biological properties of modified composite resins.MATERIALS AND METHODS: Bioglass powder(45S5,?7.26?m)was mixed into resin matrix with different mass ratio(0 wt%,8wt%,16wt%,23wt%)to prepare new composite resin.The total inorganic filler content of each group of resin were 76wt%;The flexural strength,compressive strength and microhardness were evaluated by Universal testing machine and microhardness tester;the antibacterial effect on Streptococcus mutans was evaluated by direct contact and extracting method,and the scanning electron microscope was used to detect the effects of bioactive glass modified composite resin on dentin surface mineralization in simulated body fluids after 21 days of soaking with tooth sections and composite resin.Finally,the cytotoxicity was evaluated by agar overlay method and MTT method.RESULTS:(1)A novel bioactive glass modified composite resin was successfully prepared in this study.When the mass ratio was in the range of 8 wt% to 23 wt%,the incorporation of bioactive glass did not affect the flexural strength and compressive strength of the composite resin.When the mass ratio is 16 wt% or more,the incorporation of bioactive glass decreased the hardness of the composite resin;(2)With the increase of the content of bioactive glass,the antibacterial effect of the modified composite resin is stronger and positively correlated.The decisive factor for exerting the antibacterial effect comes from the ions released by the bioactive glass(such as calcium ions)and high p H.The antibacterial mechanism is related to the bacterial cell membrane damage leading to the enhanced melting activity of Streptococcus mutans;(3)When the mass ratio is 16 wt% and 23 wt%,the modified composite resin can induce the formation of lamellar or thick hydroxyapatite on the surface of dentin,almost completely sealing the dentinal tubules,and the degree of dentin mineralization is closely related to the ratio of addition of bioactive glass;its mechanism may be closely related to calcium,silicon ion release and p H;(4)The agar overlay method showed that the cytotoxicity of the modified composite resin was 0?1 when the mass ratio was 8 wt%?16 wt%,and the cytotoxicity of the modified composite resin was grade 2 when the mass ratio was 23 wt%.The MTT method showed that when the bioactive glass content exceeded 16wt%,the extract of the modified composite resin had obvious cytotoxicity,but no dose dependent correlation;after adjusting the p H value of the extract to neutral,the cell viability of each group was obvious elevated,suggesting that cytotoxicity is closely related to the increase in p H in the culture medium.Conclusions: Bioactive glass can impart good antibacterial and dentin mineralization ability to composite resin.When the mass ratio is between 8 wt% and 16 wt%,the mechanical properties and cytotoxicity of the modified composite resin meet the standards for medical devices,indicating a promising clinical application prospects.The antibacterial,dentinal mineralization and cytotoxicity mechanisms are closely related to calcium,silicon ion release and p H value,suggesting that its antibacterial and biological properties can be controlled by changing the calcium and silicon ratios and regulating p H values of the materials,which provides scientific data and theoretical support for the optimization and improvement of bioactive glass modified composite resins.