Urinary excretion levels of nickel in orthodontic patients

Nickel, a primary component of orthodontic appliances, causes more allergic reactions than all other metals combined and can initiate a wide range of hypersensitivity reactions in susceptible subjects. The purpose of this study was to compare pretreatment and treatment levels of nickel in the urine of orthodontic patients wearing fixed appliances.Urine specimens were collected from 21 orthodontic patients (12 female, 9 male) before placement of orthodontic appliances and 2 months after placement. Nickel ion analysis was carried out with atomic absorption spectrophotometry. The results were submitted to descriptive analyses, the Student t test, and ANOVA for repeated measurements (P <.05).Urinary nickel levels increased significantly 2 months after the placement of orthodontic appliances. The results were similar in both sexes. Continued follow-up is needed to determine the patterns and the long-term significance of nickel release.