| ObjectThe clinical application of medical implants is radically based on the integration,growth and fusion of tissues between the implants and bone tissues.The"osseointegration theory"regards the perfect bone-bonding between implant and bone as a key factor for a successful implanting operation.Many of clinical investgations have shown that the physical and chemical properties of the implant,mechanical properties and local infection after implantation are the two key factors influencing the success of the surgery.Titanium?Ti?and its titanium alloy?Ti6Al4V?are the most extensively used implant materials in clinical medicine,which have good physical and chemical properties,biocompatibility and bone-bonding properties,and these characteristics are the gold standard of medical implant materials.However,due to its susceptibility to oxidation,pure titanium can easily form dense oxide films in the air,resulting in its biological inertia and anaphylaxis caused by ion releasing.In addition,there are large amounts of oral microbes in the complicated microenvironment,which will inevitably form bacterial retention and colonization around the implant during the process of osseointegration.The body's cells and microorganisms will be competitive in attached on the surface of the implant material,once the immune response balance of host is tipped by bacteria,which arouses infection around implants and eventually results in the failure of dental implant surgery.At present,it is very essential to develop certain functional materials to prevent the infection around the implant since the lack of effective treatment.Therefore,this study modified pure titanium and titanium alloy based on different material modification methods,and endowed them with good biocompatibility,anti-bacterial and anti-inflammatory properties,and evaluated its impact on the genetic diversity of oral microbial communities,so as to provide an optimal strategy for both repair and reconstruction of bone tissue and induction of soft tissue regeneration in medical clinic.Methods?1?Yttrium hydroxyapatite?Y-HA?coating with different concentrations was prepared on the surface of titanium by Sol-Gel method.The microstructure of the coating was characterized by SEM,AFM,XRD and XPS.Human gingival fibroblasts?HGF?were inoculated on the surface of each group of samples and cultured for 1,3and 5 days.The proliferation capacity of cells was detected using the CCK-8 method.SEM and AFM were used to observe adhesive condition of cells,and ELISA was applied to detect the Col-1 secretion by HGF cells.Streptococcus mutans were cultured on the samples to test the antibacterial properties of the coating.?2?Micro-arc oxidation technique was used to prepare microcellular coating containing different concentrations of yttrium?Y?titanium dioxide?Ti O2?,and using SEM,AFM,XRD and XPS characterized the microstructure of coating.Immunofluorescence technique?IF?and western blot?WB?approach were applied to analyze the coating's effect on both cell morphology and multiplication of Mouse Embryonic Preosteoblast Cells?MC3T3-E1?and HGF and expression of relative bone morphogenetic protein and gene.Lastly,culturing Escherichia coli and Staphylococcus aureus on the surface of the modified material tested the antibacterial properties of the coating.?3?Based on the genetic perspective,the effect of novel modified coating materials on the genetic diversity of oral flora was investigated to evaluate its antibacterial ability.Selected healthy adults'saliva was co-cultured with the new materials in experiment 1 and 2,and saliva was compared without culture.The effect of the new materials on genetic diversity of oral flora was analyzed by 16Sr-DNA high-throughput sequencing and bioinformatics.?4?In vivo zebrafish material implantation model was established to investigate the anti-inflammatory properties of the coating materials.Here,Y0-Ti,Y7-HA-Ti and Y9-Ti O2 composite materials were implanted into the inferior abdominal cavity of zebra fish in the form of titanium wire surface coating,and then positioned in the hip muscle tissue to observe the inflammatory response of the tissues.The anti-inflammatory effect of the implanted materials on zebra fish in vivo was evaluated to detect the expression of inflammatory factors by the ELISA and observe the tissue morphology.Results1.a)The results of material characterization showed that the hydroxyapatite coating mixed with different yttrium concentrations was successfully prepared on the surface of the titanium sheet,and doped yttrium did not significantly affect the microstructure,roughness,crystal phase structure and other basic physical and chemical properties of the hydroxyapatite coating.b)The results of cell experiment indicated that the proliferation of cells in the group doped with Y-HA coating was superior to pure Ti.The morphology of HGF cells on the surface of pure titanium material doped with Y7-HA coating was better than that in the other groups,and the cell rigidity in the HA group and the Y7-HA group was significantly higher than that in the Ti group.c)Molecular experiments indicated that the Col-1 level of HGF synthesis was proportional to the doping concentration of Y and the cell culture time;d)Antibacterial experiments exhibited that Y7-HA could reduce the proliferation and adhesion of Streptococcus mutans.2.a)The material science characterization experiment indicated that the yttrium-doped Ti O2 coating?Y-Ti O2?was successfully prepared in the experiment,and the basic physical and chemical properties of the coating were not significantly changed compared with those of the yttrium-doped Ti O2 microcellular coating.b)The cytological results showed that the proliferation capacity of MC3T3-E1 and HGF on the surface of yttrium-bearing titanium dioxide coating material was significantly enhanced compared with that of the control group;c)Molecular experiments showed that on days 1,3 and 7,the expression levels of ALP,TGF-?and BMP-2 in the material group,which coated with yttrium titanium dioxide,all increased,and the amount of alizarin red mineralized calcium nodules was positively correlated with the amount of yttrium concentration doping.d)Antibacterial test showed that the yttrium coating with high concentration had certain antibacterial properties.3.The antibacterial implant materials produced by different surface treatments had no significant effect on the overall diversity of oral microbial community.Moreover,no changes were observed in?diversity and?diversity,and no significant changes in the abundance and species of bacteria in the oral cavity were observed.However,the abundance of actinomyces and their bacilli in the oral cavity decreased.4.After composite material implantation,there was no difference in the levels of the related inflammatory factors,IL-6 and TNF-?,and the tissue morphology of zebra fish muscle tissue in the three groups showed slight inflammatory reaction,but no significant difference was observed in the degree of inflammatory cell infiltration between the three groups under the microscope.Conclusion1.The Y-HA coating on the surface of pure titanium can improve the biocompatibility and reduce bacterial adhesion,,which shows the certain antibacterial properties.This kind of coating can not only reduce the abundance of harmful bacteria such as actinomyces in oral cavity,but also have no significant effect on the whole flora of saliva.Therefore,this novel coating material has potential applications for medical implants and can promote the integration and regeneration of the surrounding soft tissue.2.Yttrium-doped titanium dioxide coating has good biocompatibility and high concentration yttrium has superior antibacterial properties.Therefore,yttrium-doped titanium coating can promote and induce the integration,repairing and regeneration of hard tissue and soft tissue around the implant,suggesting that the novel modified material may has a good application prospect for implantation.3.This experiment revealed the inflammatory reaction of the modified titanium material,and confirmed that the modified material did not cause a strong inflammatory reaction and did not aggravate the production of inflammation,which provided an experimental basis for its application in clinical implantation. |
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