NICKEL HYPERSENSITIVITY REACTION BEFORE, DURING, AND AFTER ORTHODONTIC THERAPY

Nickel is a strong biological sensitizer and consequently may induce a delayed hypersensitivity reaction (type IV immune response). Because nickel is a component of the majority of the orthodontic alloys, the o bjectives of this cross-sectional study were to determine the prevalen ce of nickel hypersensitivity reaction before, during, and after ortho dontic therapy with conventional stainless steel brackets and wires; t o evidence the induction of this reaction by the orthodontic appliance s; and to characterize the nickel hypersensitive persons. Nickel patch tests and a questionnaire were used to evaluate the hypersensitivity to this metal. The total sample consisted of 170 patients, 105 females and 65 males, from the orthodontic department at Bauru Denial School, University of Sao Paulo. They were divided into three groups as follo ws: A (n = 60), patients before the beginning of orthodontic therapy; B (n = 66), patients currently undergoing orthodontic treatment, and C (n = 44), patients who had undergone orthodontic treatment previously . The chi-square test (chi(2)) showed an allergic reaction in 28.3% of the total sample with 23% female and 5.3% male. This indicated a gend er difference (chi(2) = 10.75, p < 0.001). There was a positive associ ation between nickel hypersensitivity and previous personal allergic h istory to metals (chi(2) = 34.88, p < 0.0001) as well as with the dail y use of metal objects (chi(2) = 11.95, p < 0.0005). There was no stat istically significant difference in the prevalence of contact dermatit is among the three groups (chi(2) = 0.39, p = 0.848). This suggests th at orthodontic therapy with conventional stainless steel appliances do es not initiate or aggravate a nickel hypersensitivity reaction.