Ceramics-Silikáty 54 (3) 241-247 (2010)

INFLUENCE OF HEAT TREATMENT ON THE IN VITRO BIOACTIVITY OF ALKALI-TREATED TITANIUM SURFACES

M. Ravelingien , S. Mullens , J. Luyten , V. Meynen , E. Vinck , Ch. Vervaet , J.-P. Remon

Alkali- and heat-treated titanium surfaces have earlier shown bioactivity. However, sufficient attention has to be paid to the sensitivity of porous titanium substrates to oxidation and nitriding during heat treatment under air. Therefore, in the present study, alkali-treated titanium samples were heat-treated under air, argon flow or vacuum. They were extensively characterized by contact angle measurements, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, field emission scanning electron microscopy (FESEM), thin film X-ray diffraction (TF-XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and glow discharge optical emission spectroscopy (GDOES). The in vitro bioactivity was evaluated in simulated body fluid (SBF). All heat treatments under various atmospheres turned out to be detrimental for apatite deposition. They led to the thermal decomposition of the dense sodium titanate basis near the interface with the titanium substrate into atmospheredepending forms of Ti_yO_z and sublimated Na₂O. Consequently, less exchangeable sodium ions remained available. This points to the importance of the ion exchange capacity of the sodium titanate layer for in vitro bioactivity.