Long-term assessment of the implant titanium material--artificial saliva interface.

This paper studies the long-term (20,000 exposure hours) behavior of titanium and Ti-5Al-4V alloy-Carter-Brugirard saliva interface and the short-term (500 exposure hours) resistance of titanium and Ti-5Al-4V alloy-Tani&Zucchi saliva interface. Potentiodynamic polarization method was applied for the determination of the main electrochemical parameters. Linear polarization measurements for to obtain the corrosion rates were used. Monitoring of the open circuit potentials (E(oc)) for long-term have permitted to calculate the potential gradients due to the pH, DeltaE(oc)(pH) and to the saliva composition DeltaE(oc)(c) changes which can appear "in vivo" conditions and can generate local corrosion. Atomic force microscopy (AFM) has analyzed the surface roughness. Ion release was studied by atomic absorption spectroscopy (AAS). In Carter-Brugirard saliva both titanium and Ti-5Al-4V alloy present very stable passive films, long-term stability, "very good" resistance, low values of the open circuit potential gradients, which cannot generate local corrosion. In Tani&Zucchi artificial saliva, pitting corrosion and noble pitting protection potentials (which cannot be reached in oral cavity) were registered; titanium ion release is very low; surface roughness increase in time and in the presence of the fluoride ions, denoting some increase in the anodic activity.