Hypersensitivity to metals in orthodontics.

To study the incidence of hypersensitivity to orthodontic metals, patch tests were carried out before and 2 months after the placement of orthodontic appliances in 38 patients (17 male, 21 female). The tested substances were cobalt chloride, copper sulfate, potassium dichromate, iron sulfate, manganese chloride, molybdenum salt, nickel sulfate, and titanium oxide. Eight strips containing the test substances were positioned on the patients' backs. They were removed after 48 hours and assessed by a dermatologist at 48 and 72 hours after antigen application. The obtained data were analyzed by the chi-square test and McNemar's chi-square test. Statistically significant positive reactions were observed for nickel sulfate (21.1%), potassium dichromate (21.1%), and manganese chloride (7.9%); reactions to nickel sulfate had the greatest intensity. No differences were observed between the reactions before and after placement of the orthodontic appliances; this indicates that they did not sensitize the patients or affect their tolerance to these metals during the study period. No statistical difference was observed regarding sex for any evaluated substance, although a greater tendency to positivity to nickel sulfate was observed among female patients and to potassium dichromate in male patients.