Nickel allergy: blood and periodontal evaluation after orthodontic treatment.

The aim of this study was to assess periodontal status and blood parameters in orthodontic patients with nickel allergy one month after removal of brackets. Ninety-six randomly selected patients were initially evaluated. Allergy to nickel was diagnosed using a patch test. After determining the prevalence of subjects allergic to nickel, two groups were formed: 16 allergic (experimental) and 16 non-allergic (control) patients. Their periodontal status was determined regularly by a single, blinded, duly calibrated examiner using the Loe Index (GI) and their blood was tested (complete blood test, including nickel and IgE levels) after nine months of orthodontic treatment and again one month after removing the orthodontic appliances. Statistical analyses included paired and non-paired t-tests, Mann-Whitney, Wilcoxon, McNemar and linear trend chi-square tests (p</=0.05). Comparison of the values recorded during orthodontic treatment and one month after removing the appliances showed that in the allergic group there was significant increase in eosinophils (p=0.046), basophils (p=0.001) and monocytes (p=0.002), and decrease in number of bands (p=0.000), while in the control group, there was increase in lymphocytes (p=0.039) and decrease in segmented neutrophils (p=0.030) and IgE levels (p=0.001). In both groups, plasma nickel levels increased (p=0.010; p=0.039) and GI scores decreased. One month after removing the brackets, blood and periodontal parameters from patients with and without nickel allergy were similar.