Galvanic corrosion of dental amalgams in contact with titanium in terms of released ions

Galvanic corrosion between dental amalgams and titanium was examined in terms of released ions. The ions released from the dental amalgams in contact with titanium at surface area ratios of titanium/amalgam in a range of 1/10-10/1 were quantitatively analyzed after being immersed in 0.9 mass% sodium chloride solution at 310K for 6.05 × 10⁵ s. The potentials and the anodic polarization curves were also measured under the same conditions. Furthermore, the amalgam surfaces after immersion were analyzed using WDS. Each potential of the conventional amalgams was always lower than that of titanium, though each potential of the high-copper amalgam was reversed in the early stage of immersion and was also lower. When the surface area ratio did not increase to over 1/1, each total amount of ions released from the amalgams in contact with titanium was a little larger or smaller than that released from amalgams not in contact with titanium. However, tin and copper ions released from the conventional amalgams and the high-copper amalgam, respectively, increased greatly when the ratio grew to 10/1. Each amount of released ions with titanium, except mercury ions, was approximated by the equation W_with = a × (W_without)^b, where the coefficients "a" and "b" are constant and W_with and W_without mean each amount of the released ions with and without titanium, respectively. The coefficient "b" probably relied on the surface area ratio and immersion time. When the ratio grew to 10/1, the amount of released ions with titanium, except mercury ions, could be shown by the equation W_with = a × (W_without) at a = 4.202-9.982. Since the contact with titanium seemed to drastically make the amount of mercury ions decrease, the mercury ions did not fit this equation. These results indicated a risk of galvanic corrosion between dental amalgams and titanium with a large surface area ratio.