The aim of the present study was to assess gingival status and blood parameters one month after the removal of braces in patients with nickel allergy. Ninety-six patients were initially evaluated. Allergy to nickel was diagnosed using a patch test. After the determination of the prevalence of those allergic to nickel, two groups were formed: 16 allergic and 16 non-allergic patients. Gingival status was determined using the gingivalindex. Humoral characteristics were determined through a complete blood test, including the quantification of nickel in the blood and IgE levels. Assessments of periodontal status were determined by a single, blinded, duly calibrated examiner and blood samples were taken after nine months of treatment and one month after removing the orthodontic appliances. Statistical analysis involved paired and non-paired t-tests,the Mann-Whitney, Wilcoxon, McNemar and linear trend chi-square tests (p.0.05). The number of eosinophils, basophils and monocytes increased, whereas the number of bands decreased between periods in the allergic group compared with controls (p 0,90) e amostras de sangue foram colhidas durante o tratamento ortodontico (9 meses) e um mes apos a remocao de aparelhos ortodonticos. A analise estatisticaenvolveu testes t pareado e nao pareado, Mann-Whitney, Wilcoxon, McNemar e quiquadrado de tendencia linear (p.0,05). O numero de eosinofilos, basofilos e monocitos aumentou enquanto o numero de bastoes diminuiu em ambos os periodos no grupo alergico (p<0,05). O numero de linfocitos aumentou significativamente no grupocontrole (p<0,05). O indice gengival diminuiu significativamente em ambos os grupos durante e apos o tratamento. Os resultados do presente estudo analisando o periodo de contato direto com o agente alergenico e apos a sua remocao indicam que o tratamentoortodontico com aparelhos de aco inoxidavel convencionais nao iniciar ou agravar uma reacao de hipersensibilidade ao niquel
