[Effect of fluoride ion on corrosion of two dental titanium alloys]

To investigate the effect of fluoride concentration on the corrosion behavior of Ti-12Zr alloy and Ti-6Al-4V alloy in a simulated oral environment.

Each specimen was put into the acidic artificial saliva (pH = 4.0) with different NaF concentration (0%, 0.05%, 0.1%, 0.2%) and electrochemical experiment was carried out. Then the surface microstructure and compositions of specimen were analyzed by scanning electron microscope (SEM) after immersed in the test solution with constant temperature.

The corrosion potential (E(corr)) and polarization resistance (R(p)) values of titanium alloy decreased with the increasing of NaF concentration, while the corrosion current density (I(corr)) values increased with the increasing of NaF concentration in acidic artificial saliva. The E(corr), R(p) and I(corr) values of titanium alloy changed significantly when the NaF concentration was over 0.1% (P < 0.05). The R, between Ti-12Zr alloy and Ti-6Al-4V alloy had a statistically significant difference, and the R(p) of Ti-12Zr alloy was higher than that of Ti-6Al-4V alloy when the NaF concentration was 0.2% (P < 0.05).

The fluoride ions have a negative influence on the corrosion resistance of Ti-12Zr alloy and Ti-6Al-4V alloy, especially in the acidic artificial saliva which contained over 0.1% NaF.