Inhibitory Effect Of Chitosan (CTS) And Silver Nanoparticles (AgNPs) On Oral Pathogens In Implant Denture Screw Channels In Vitro

Objective The species and relative abundance values of oral pathogens in the implant denture screw channel were detected,and the inhibitory effect of chitosan and nanosilver on specific periodontal pathogens in the implant denture screw channel was studied.Methods 1.Detection of oral pathogenic bacteria in the implant denture screw channel:13 periodontal disease patients who met the experimental requirements for implant denture restoration and functional load after 1 month,3 months,1 year,3 years and above(implant model Straumann BL)were selected to sample the microorganisms on the PTFE band in the screw channel of screw-retained implants,and the species and relative abundance values of the microorganisms on them were detected by high-throughput sequencing technology(NGS)with high sensitivity.2.Antibacterial study of chitosan and nanosilver on specific oral pathogenic bacteria:using Colombian blood medium to culture Porphyromonas gingivalis(Pg),Actinomyceus actinomyceus(Aa),and Fusobacterium nucleatum(Fn).The diameter of the bacteriostatic ring formed by chitosan and nanosilver drugs against Pg/Aa/Fn was measured by single drug susceptibility test.The minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)of CTS and AgNPs on Pg/Aa/Fn were detected by the Oxford cup method,and the difference between CTS and AgNPs on Pg/Aa/Fn inhibition at different concentrations was studied by MTT colorimetry.Results 1.The dilution curves of the 13 study samples in this experiment tend to be flat overall,indicating that the amount of sequencing data in this study is reasonable.At the phylum level,the top 10 phylums on the sample were:Firmicutes;Actinobacteria;Proteobacteria;Bacteroidetes;Synergistetes;Fusobacteria;Proteo-bacteria;Campilobacterota;Spirochaetae;Euryarchaeota.The three oral pathogens with high periodontal destruction correlation and detection rate were as follows:Actinoagilibacter actinoagiliensis(Aa),Fusobacterium nucleatus(Fn),and Porphyromonas gingivalis(Pg).There were no significant differences in Chao 1 richness index,Shannon diversity index and Simpson index in A,B,C,and D of the four groups of microbial diversity analysis(P>0.05).2.The average diameter of the antibacterial ring of Pg was 10mm,the average diameter of the antibacterial ring of Aa was 12.4mm,and the average diameter of the antibacterial ring of Fn was 10.1mm of 1mg/ml of AgNPs;the average diameter of the antibacterial ring of Pg was 19.7mm,the average diameter of the antibacterial ring of Aa was 21.7mm,and the average diameter of the antibacterial ring of Fn was 21.4mm;the minimum inhibitory concentration of AgNPs on Pg was 16μg/ml,the minimum inhibitory concentration for Aa is 8μg/ml,and the minimum inhibitory concentration for Fn is 8μg/ml.However,in the CTS Oxford cup bacteriostatic experiment,the antibacterial ring around the Oxford cup was not obvious,and the minimum inhibitory concentration could not be accurately measured.The minimum sterilization concentration of AgNPs for Pg is 31μg/ml,the minimum sterilization concentration for Aa is 16μg/ml,and the minimum sterilization concentration for Fn is 31μg/ml.The minimum sterilization concentration of CTS for Pg is 250μ/ml,the minimum sterilization concentration for Aa is 125 μg/ml,and the minimum sterilization concentration for Fn is 250μ/ml.The absorbance value(OD490)was detected by MTT method when different concentrations of CTS and AgNPs acted on Pg/Aa/Fn,and the data showed that the measured OD value was different under different concentrations of CTS and AgNPs.At the same concentration,the measured OD value of AgNPs was smaller than that of CTS.However,with the increase of the concentration of both drugs,the OD value showed a downward trend.Conclusion 1.Micro-leakage of implant-abutment interface and crown screw hole is a common phenomenon,and under functional load and different repair times,oral pathogenic bacteria contamination is generated in the implant screw channel of periodontal disease patients.2.The diversity of oral pathogenic bacteria community in the implant screw channel is not directly related to the functional loading time of the implant,and the oral pathogenic bacteria enter the interior through the microleakage of the implant-abutment in the early stage of implant restoration and continue to propagate.3.Chitosan and nanosilver have obvious inhibitory effects on the growth of oral pathogenic bacteria Porphyromonas gingivalis(Pg),Actinoagilibacterium aggregates(Aa),and Fusobacterium nucleatus(Fn),and the inhibitory effects of both drugs are concentration-dependent,but nanosilver has a stronger bacteriostatic effect on these three specific oral pathogens than chitosan.