INTRODUCTION: Our aims in this study were to assess adverse patient reactions during orthodontic treatment with nickel-containing appliances and to investigate the need for and the use of nickel-free devices in orthodontic practices in Finland and Norway. METHODS: A questionnaire was mailed to orthodontists and dentists versed in orthodontics in both countries. They were asked to retrospectively assess the number of patients with adverse reactions and to describe the reactions, the appliances used, and any implications on treatment. Previous history of nickel allergy of patients with adverse reactions, and use of and need for nickel-free appliances in clinical practice were also addressed.
RESULTS: Forty-six percent of the respondents (n = 298) reported at least 1 adverse patient reaction during the last 5 years. More than half of the reactions had implications for the treatment. Finnish respondents observed significantly more adverse patient reactions than their Norwegian colleagues, and, in Finland, the adverse reactions were most frequently attributed to headgear treatment. Using nickel-containing fixed appliances in nickel-allergic patients was more common in Finland (77% of the respondents) than in Norway (65%).
CONCLUSIONS: Nearly half of the dentists regularly working with fixed appliances had observed at least 1 adverse patient reaction during treatment. Nickel-containing fixed appliances are generally used in most patients-even those with a suspected nickel allergy.

Adverse patient reactions during orthodontic treatment with fixed appliances
Kerosuo HM, Dahl JE.
American Journal of Orthodontics and Dentofacial Orthopedics 2007; 132: 789-795.