Effect Of Fluoride Ions On Corrosion Behavior Of Two Titanium Alloy For Dental Use

Objective:The purpose of this study was to investigate the effect of fluoride concentration on the corrosion behavior of Ti-12Zr alloy and Ti-6Al-4V alloy with electrochemical test,scanning electron microscopy (SEM) and energy dispersive spectrometry(EDS) in a simulated oral environment.Method:Ti-12Zr alloy and Ti-6Al-4V alloy specimens were randomly divided into four groups which contained different NaF concentration(0,0.05,0.1,0.2%).After the surface pre-treated,each specimen was put into the acidic artificial saliva(pH=4.0) with different NaF concentration and carried out electrochemical experiment.Then the surface microstructure and compositions of specimen were analyzed by SEM and EDS after immersed in the test solution with constant temperature(37.0±1.0℃) for 2 weeks.Result:1.The corrosion potential(E_corr) and polarization resistance(R_p) values of Ti-12Zr alloy and Ti-6Al-4V 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.2.The E_corr,R_p and I_corr values of Ti-12Zr alloy and Ti-6Al-4V alloy changed significantly when the NaF concentration was over 0.1%in acidic artificial saliva(P＜0.01).Similarly,more serious corrosion occurred on the surface of these two kinds of titanium alloy according to the result of SEM when the NaF concentration was over 0.1%.3.The Rp between Ti-12Zr alloy and Ti-6Al-4V alloy had a statistically significant difference(P＜0.01) and the R_p of Ti-12Zr alloy was higher than that of Ti-6Al-4V alloy.4.It revealed that the oxygen content of specimen surface increased with the increasing of the NaF concentration in acidic artificial saliva according to the result of EDS.Conclusion:1.The fluoride ions had 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,the corrosion tendency became more obviously and the corrosion rate increased more quickly.2.The fluoride ions had less influence on the corrosion resistance of Ti-12Zr alloy.It seemed that the corrosion resistance of Ti-12Zr alloy was better than that of Ti-6Al-4V alloy in the acidic oral environment with fluoride.