Commercially Pure Titanium and Ti6Al4V: XPS Comparison Between Different Commercial Ti Dental Implants and Foils Prepared by Various Oxidation Procedures

Commercially pure (c.p., 99.6%) titanium and the Ti6Al4V alloy are widely used in biomedical applications. The surface (oxide) properties of these materials play a key role for their function in biomaterial applications, and it is therefore important to analyze their surface composition. XPS survey and high resolution spectra (Ti 2p, O 1s, and C 1s) are presented from three commercially available dental implants, all manufactured by machining but with different post treatments (grit blasting, cleaning, sterilizing, and packaging). Comparison is made with a TiO2 single crystal (rutile (110)) reference sample, and with Ti and Ti6Al4V foils prepared by the following treatments commonly used for titanium biomaterials: ASTM F86/B600 passivation, electropolishing in perchloric acid based electrolyte, anodization in sulfuric acid and phosphoric acid, and glow discharge plasma oxidation. Survey spectra from the implants are qualitatively similar but quantitatively different, with Ti, O, and C as the main elements and trace amounts of preparation-specific impurities. The high resolution spectra show differences in oxide composition (varying deviations from pure TiO2 stoichiometry), thickness, and carbon overlayer composition. Spectra from the differently prepared Ti and Ti6Al4V foils showed preparation-specific differences mainly with respect to oxide composition, oxide thickness, and trace impurities. For the Ti6Al4V the different preparations lead to various amounts of detected Al. A general difference between the differently prepared Ti and Ti6Al4V foils was that Al and V were always detected on the latter, but only sporadically on the Ti. These results clearly show that the composition of titanium surfaces varies considerably depending on the surface preparation used. Important implications are: (i) surface preparation and characteristics need to be considered when results from biological studies on Ti surfaces are interpreted and compared, (ii) Ti and Ti6Al4V form oxides with different composition, and (iii) different commercial Ti implants cannot a priori be assumed to have similar surface composition.