Some reports show that fluoride may induce corrosion of alloys. Nakagawa et al. reported that pure titanium and titanium alloys were corroded by fluoride at half or less than half of the concentration currently found in commercial dentifrices less than 453 ppm fluoride. Watanabe et al. reported that several applications of acidulated fluoride agents may cause discoloration of β-titanium alloy wires. However, these problems occurred with excessive fluoride concentrations and at low pH; these conditions are unlikely to arise during clinical use.
