Study On The Preparation And Properties Of Composite Silver-loaded Nano-titanium Dioxide Thermoplastic Gutta-percha

Objective:To construct bacteriostatic thermoplastic root canal filling material with good sealing property and clarify its properties.Methods:Different proportion（mass fraction of 0%,0.5%,1%,2%,4%）of silver-loaded nano-Ti O₂ antibacterial agent（Ag/Ti O₂）was uniformly mixed into thermoplastic gutta-percha under heating condition to form composite materials,and thermoplastic gutta-percha specimens containing different concentrations of antibacterial agent were prepared.In order to test its properties,a round sample of thermoplastic gutta-percha with a diameter of 8.0mm and a thickness of 1.5mm was prepared.According to the difference of Nano Ag/Ti O₂ mass fraction in the composite silver-loaded nano-titanium dioxide thermoplastic gutta-percha samples,and the extracts were prepared for each group.CCK-8 reagent was used to detect the effects of each group of extracts on the proliferation of L929 cells（mouse fibroblast）at the first,second and third days in vitro,and the cytotoxicity of each group was determined;Agar diffusion test,bacterial adhesion test and bacterial metabolic activity test were used to observe the antimicrobial and antimicrobial adhesion properties of specimens against S.aureus,E.coli and E.faecalis;Dye penetration method was used to detect root canal microleakage of each group after root canal filling,and the sealing ability of root canal was evaluated.Results:With the increase of the concentration of antibacterial agent Nano Ag/Ti O₂,compared with the blank control group,the cell proliferation rate of each composite thermoplastic gutta-percha extract group decreased,except 4wt%concentration group,the difference was not statistically significant（P>0.05）,the cytotoxic level is 0-2;Compared with the thermoplastic gutta-percha without Nano Ag/Ti O₂,the root canal sealing and bacteriostasis of the experimental group were stronger（P<0.05）.Conclusion:The toxicity of composite silver-loaded nano-titanium dioxide thermoplastic gutta-percha to L929 cells in vitro was 0-2,comply with biomaterial safety standards;The antimicrobial properties and antimicrobial adhesion ability of the composite Nano Ag/Ti O₂ thermoplastic gutta-percha material were significantly improved;Composite Nano Ag/Ti O₂ thermoplastic gutta-percha material has better root canal sealing.The optimal addition amount of Nano Ag/Ti O₂ is 2.0wt%.