Development of dental titanium alloys with high corrosion resistance in fluoride environment

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The effects of dissolved-oxygen concentration and fluoride concentration on the corrosion behaviors of commercial pure titanium (Ti), Ti-6A1-4V and Ti 6A1-7Nb alloys and experimentally produced Ti-0.2Pd and Ti-0.5Pt alloys were examined by the corrosion potential measurements, dissolved Ti analyses and surface analyses of the specimen. Pure Ti, Ti-6A1-4V and Ti-6A1-7Nb alloys were easily corroded even in a low fluoride concentration in an acidic environment. The corrosion resistance of Ti-0.2Pd and Ti-0.5Pt alloys were greater than those of pure Ti, Ti-6A1-4V and Ti-6A1-7Nb alloys in the wide range of pH and fluoride concentrations. The high corrosion resistance of Ti- 0.2Pd and Ti-0.5Pt alloys were caused by the surface enrichment of Pd or Pt promoting a repassivation of Ti.Decrease in the dissolved-oxygen concentration tended to have reduced the corrosion resistance of Ti and Ti alloys. Under the low, dissolved-oxygen environment, the corrosion of pure Ti and Ti-6A1-4V and Ti-6A1-7Nb alloys might easily take place in the presence of small amount of fluoride. They were corroded by the half or less fluoride concentration in commercial dentifrices (1OOOppmF). The Ti-0.2Pd and Ti-0.5Pt alloys did not corrode even under the low dissolved-oxygen concentration and fluoride-containing environment. These alloys are expected to be useful as new Ti alloys with high corrosion resistance in dental use.