Nickel and iron in saliva of patients with fixed orthodontic appliances

Saliva was obtained from patients receiving treatment with fixed orthodontic appliances. One saliva sample was taken without appliances, and another at least 3 weeks after placement. In some patients samples were also taken immediately after insertion of the appliance. Nickel and iron were quantified by electrothermal atomic absorption spectroscopy. There was a large scatter in the results. No statistically significant differences were found either in the concentrations or in absolute masses of nickel or iron in samples taken without appliances and in those obtained when the appliances had been in the mouth for at least 3 weeks. For samples taken immediately after placement of the appliance, there was a significant increase in both concentrations and masses of nickel and iron. It thus seems that there is a high initial release of metals, and the effect diminishes with time.