Nickel concentration in the saliva of patients with nickel-titanium orthodontic appliances.

INTRODUCTION: The purpose of this study was to examine whether nickel-titanium (Ni-Ti) archwires cause an increase of nickel concentration in the saliva of 18 orthodontic patients to estimate the possible risk of these archwires in patients who have nickel hypersensitivity. METHODS: Saliva samples were collected before orthodontic treatment, after placement of the bands and brackets, 2 weeks later and before placing the Ni-Ti archwires, immediately after placing the Ni-Ti archwires, 4 weeks after placing the wires, and 8 weeks after placing the wires. RESULTS: By using mass spectrometry, no statistically significant differences were found in the nickel concentrations in the samples taken without appliances, in those obtained 2 weeks after placement of the bands and brackets, and 4 and 8 weeks after placement of the archwires. Samples taken immediately after placement of the bands and brackets and the Ni-Ti archwires showed slight but significant increases in nickel concentration of 78 and 56 microg per liter, respectively, compared with the pretreatment value of 34 microg per liter. CONCLUSIONS: Nickel leaching occurred after placement of the bands and brackets and after placement of the Ni-Ti archwires, associated with an increase of the nickel ion concentration in the patient's saliva. This effect decreased within 10 weeks.