Nickel sensitization in orthodontically treated and non-treated female adolescents

Background. The importance of the nickel exposure from fixed orthodontic appliances is under continuous discussion. Objectives. Our aim was to investigate nickel allergy and the risk of nickel sensitization among female adolescents during orthodontic treatment with fixed appliances as compared with non-treated female adolescents. Subjects and methods. Female patients starting or with ongoing orthodontic treatment (n = 30) and young females without a history of orthodontic treatment (n = 140) were studied. Patch testing with 5% nickel sulfate was carried out twice on each participant with an approximately 1-year interval. The subjects completed a questionnaire before the first testing. Results. None of the 7 orthodontic patients with a positive patch test reaction to nickel had any clinically visible intraoral allergic symptoms during their treatment. No significant difference was seen in the occurrence of positive nickel reactions in regard to orthodontic treatment, or between the first and second tests. In the treatment group, 2 patients changed from nickel-positive to nickel-negative during the observation period, and one patient showed an opposite change. The quantity and course of changes in the repeated nickel patch test reactions did not differ significantly between the subjects with and without orthodontic treatment experience. Conclusions. Nickel sensitization from orthodontic appliances is improbable, but nickel sensitization may develop also during orthodontic treatment.