Variation of oxide films on titanium induced by osteoblast-like cell culture and the influence of an H2O2 pretreatment

Variations of titanium oxide films induced by osteoblast-like cells in a rat calvaria culture system and the influence of an H2O2 pretreatment have been investigated by using X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. For abraded titanium, the results revealed that phosphate and calcium ions may incorporate into the surface oxide film during the cell culture, forming a precipitate with a Ca/P ratio near that of hydroxyapatite. Oxidized carbon also was found in the surface layer, most likely precipitated hydroxylcarbonated apatite (HCA). The H2O2 pretreatment of titanium in a phosphate-buffered saline solution results in a 10-fold thickened porous oxide film and large amounts of surface hydroxyl groups as well as a certain amount of phosphate ions inside the oxide film. During the cell culture, the H2O2-treated titanium surface favors the ion incorporation and precipitation of the HCA-like compound, which probably is inlaid into the oxide film. Osteoblast-like cells on the H2O2-treated titanium showed a more active morphology during the initial stage compared with cells on abraded titanium. Moreover, bone-like nodule formation and mineralization appear to be related to the precipitation of the HCA-like compound on the surface. The results are discussed with respect to corrosion resistance, ion incorporation and precipitation of the HCA-like compound on the surface, osseointegration, and bioactivity of titanium implants.