Biological Research Of Titanium Dental Implant Materials Surface Anodization And Ag-loading

To enhance the integration between dental implant and soft tissue surrounding, much work has been done about dental implant surface modifying. We chose anodization as the suface treating method, through which nanotubular surface microstructure can be obtained and this microstructure has good cyto-compatibility and bio-activity. In this study, pure titanium surface was anodized at 20V and 180mA, and then Ag nanoparticles were electrodeposited on this anodized surface. FE-SEM, XPS and AFM were employed to observe and analyze the surface characteristics such as surface micro-topograghy, element components and roughness. Contact angle and free energy also had been detected. The cyto-toxicity and anti-microbial property were evaluated according to ISO10993-5. Human gingival fibroblasts were cultured on these three different surfaces for cyto-behavior examination such as cell attachment in early stage, cell proliferation and ECM-related genes expression. Results:1. After anodization, pure titanium surface formed a TiO₂ nanotubular surface with diameter about 100nm and through Electro-deposition, massive highlighted particles adhered to this surface, which is null valence Ag particles.2. Anodization reduced the surface roughness of pure titanium surface. Intriguingly, silver loading procedure also slightly affected nanotubular surface microstructure and roughness. Ag-loaded and Ag-free TiO₂ nanotubular surface have showed little contact angles against water and diiodomethane. Accordingly, surface free energy results showed that these two kind of surfaces had higher surface free energy than polished Titanium(P<0.01), but there was no obvious difference between these two surfaces.3. Proper Ag-loaded nanotubular surface was screened and can be used for cyto-compatibility examination,which was prepared by using electrolyte containing 0.003mol/L AgNO3.4. Ag-loaded nanotubular array significantly suppressed the adherence of candida albicans and streptococcus mutans. But Ag-loaded nanotubular array showed different suppressive effects between these two microorganisms. Ag-free TiO₂ nanotube array didn't impact the adherence of streptococcus mutans, but could obviously inhabit the early adherence of candida albicans.5. The number of human gingival fibroblasts attached onto Ag-loaded/Ag-free nanotubular surfaces was less than their counterpart onto polished Ti surface. TiO₂ nanotubular surface could enhance the proliferation of human gingival fibroblasts. 6. RT-PCR results showed that in day3,6 and 9, anodized titanium surface did not affect ICAM-1 expression but could enhance the expression of Type I/III collagen,β1-Integrin, VEGF, while inhibited the expression of fibronectin. Besides, attached Ag nanoparticles showed some special bio-regulating activities of ECM-related gene expression.Conclusion:TiO₂ nanotubular surface microstructure could be formed on pure titanium samples through anodization. Ag nanoparticles can be loaded onto this surface. Ag-loaded TiO₂ nanotubular surface does not show cyto-toxicity but exhibits excellent anti-microbial activity. Anodized titanium surface can enhance the proliferation of human gingival fibroblasts and also regulate ECM-related gene expression, but the attachment of cell attachment in early stage is suppressed. Ag nanoparticles adhering to TiO₂ nanotubular surface can regulate cell behaviors. This TiO₂ nanotubular surface can be used on the transgingival part of clinic dental implant abutment and titanium denture.