The Properties Study Of Silver Bromide/Cationic Polymer Nanocomposite Modified Glass Ionomer Cements

Objective:To enhance the antibacterial properties of Fuji Ⅱ glass ionomer cements(GIC),a novel double action antimicrobial silver bromide/cationic polymer nanocomposite-AgBr/BHPVP was used as modified material.Then,the antibacterial activity,cell cytotoxicity,mechanical properties of Fuji Ⅱ glass ionomer cement supplemented with AgBr/BHPVP were investigated.Methods:Glass ionomer powder was mixed with AgBr/BHPVP by manually grinding and ultrasonic vibration according to different mass fraction of 3%、4%、5%as experimental groups,Fuji Ⅱ glass ionomer cements without incorporation of AgBr/BHPVP served as control group.Agar diffusion test was applied to observe the antibacterial ability to Streptococcus mutans(S.mutans)on days 1,7,14.Colony forming unit(CFU)counting method was employed to detect the number of surviving bacterial colonies on the surface of specimens before and after aging.The bacterial vitality of the biofilms was observed with confocal laser scanning microscopy(CLSM)and the LIVE/DEAD BacLight Bacterial Viability Kit stain.Scanning electron microscope(SEM)was used to observe the bacterial biofilm on the surface of each set of specimens.The cytotoxicity about the eluent of each group to human dental pulp cells(HDPCs)was assessed by a WST-8 assay.The surface vicker hardness number of each group specimen was measured using a Vicker microhardness tester.Results:AgBr/BHPVP-GIC showed strong antibacterial activity against S.mutans,and the 5%AgBr/BHPVP-GIC group had the strongest antibacterial activity.The diameter of the inhibition zone increased with the addition of AgBr/BHPVP(P<0.05),while the antibacterial activity did not decrease with time(P>0.05).Using CFU,the results also showed that the number of live bacteria decreased with the increase in the concentration of the antibacterial agent(P<0.05),and there was no significant difference in antibacterial performance compared with 30 days of aging(P>0.05).CLSM observations showed that the number of viable bacteria adhered to the surface of the modified specimen was significantly lower than that of the control group.The SEM results showed that with the increase of the dose of the antibacterial agent,the bacteria adhered to the surface of each test specimen gradually decreased,and the morphology of the bacteria also ruptured.The results of cytotoxicity assay showed that when AgBr/BHPVP was added at 3%,there was no statistical difference between the toxicity of the extract of the modified material on human dental pulp cells and the blank control group(P>0.05),but when the adding amount reached to 4%or 5%,the difference was statistically significant compared with the blank control group(P<0.05).Vickers hardness results showed that although the Vickers hardness value showed a downward trend with the increase in the amount of antibacterial agent added,there was no significant difference between the 3%AgBr/BHPVP-GIC group and the GIC control group(P>0.05).The difference between the else experimental groups and the control group was statistically significant(P<0.05),and there was no statistically significant difference between the 1st,7th,14th,and 30th days of aging(P>0.05).Conclusion:The GIC modified by the double antibacterial material-quaternary ammonium salt-encapsulated silver bromide nanocomposite(AgBr/BHPVP)has good antibacterial properties,but as the concentration increases,the cytotoxicity of the modified material will be correspondingly increased,while the Vickers hardness will be reduced.Based on the comprehensive antibacterial properties,cytotoxicity,mechanical properties,and aging test results,the 3%AgBr/BHPVP modified GIC has potential clinical application prospects.