Influence of surface treatments developed for oral implants on the physical and biological properties of titanium. (I) Surface characterization.

We present an investigation of the physico-chemical surface properties of commercially pure titanium coverslips which were submitted to various treatments designed to optimize their topography in view of application in oral implantology. The surface microroughness, chemical composition and water wettability were analyzed on titanium coverslips prepared by mechanical polishing, acid attack in HCl/H2SO4, after mechanical polishing or sandblasting, and titanium plasma-spray. The chemical composition has been measured by Auger electron spectroscopy. The treatments have no major influence on the surface chemical composition and all the samples display a composition approaching that of TiO2 with minor amounts of carbon, sulfur, silicon and calcium as impurities. The roughness has been measured by scanning force microscopy on an area of 20 microns x 20 microns on each sample. Polished titanium is smooth (peak-to-valley roughness 81 nm), whereas the acid-attacked surfaces exhibit a micro-roughness in the microns range (2100 nm for polished and acid attacked; 3600 nm for sandblasted and acid attacked) which is quite reproducible over large areas of the sample. The acid attacked samples present a subsurface layer which contains hydrogen below the native passivating oxide layer. Water wettability measurement shows that all surfaces are hydrophobic with a slightly higher contact angle for the acid attacked surfaces. The different treatments analyzed in this study essentially influence the surface roughness by preserving the chemical composition and the wettability properties of titanium native oxide surface layer.