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

Alkali-treated titanium samples were heat-treated under air, argon flow or vacuum and extensively characterised by contact angle measurements, DRIFT spectroscopy, FESEM, thin film XRD, Raman spectroscopy, XPS and glow discharge optical emission spectroscopy. The in-vitro bioactivity was evaluated in simulated body fluid. All heat treatments under various atmospheres were detrimental for apatite deposition. They led to the thermal decomposition of the dense sodium titanate basis near the interface with the titanium substrate into atmosphere-dependent forms of TiyOz and sublimated Na2O. Consequently, less exchangeable sodium ions remained available. This indicates the importance of the ion exchange capacity of the sodium titanate layer for in-vitro bioactivity.