Antibacterial effects and biocompatibility of titanium surfaces with graded silver incorporation in titania nanotubes

Most commercial dental implants are made of titanium (Ti) because Ti possesses excellent properties such as osseointegration. However, many types of Ti products still suffer from insufficient antibacterial capability and bacterial infection after surgery remains one of the most common and intractable complications. In this study, a dual process encompassing anodization and silver plasma immersion ion implantation (Ag PIII) is utilized to produce titania nanotubes (TiO2-NTs) containing Ag at different sites and depths. The concentration and depth of the incorporated Ag can be tailored readily by changing the PIII parameters. The Ag-embedded TiO2-NTs which retain the nanotubular morphology are capable of sterilizing oral pathogens as opposed to pure Ti plates and pristine TiO2-NTs. Biological assays indicate that the in vitro and in vivo biocompatibility of the sample plasma-implanted at a lower voltage of 0.5 kV (NT-Ag-0.5) is significantly compromised due to the large amount of surface Ag. On the other hand, the sample implanted at 1 kV (NT-Ag-1.0) exhibits unimpaired effects due to the smaller surface Ag accumulation. Sample NT-Ag-1.0 is further demonstrated to possess sustained antibacterial properties due to the large embedded depth of Ag and the technique and resulting materials have large potential in dental implants.