Prevalence of Nickel Allergy and Longitudinal Evaluation of Periodontal Abnormalities in Orthodontic Allergic Patients

Abstract

To determine the prevalence of nickel allergy in a sample of orthodontic patients and longitudinally compare the clinical periodontal status of these individuals with that of a group of nonallergic patients. The initial sample consisted of 96 patients selected randomly from a databank of patients who sought orthodontic care at a teaching institution. Following the selection and beginning of treatment, periodontal status was assessed over a 12-month period (one evaluation every 3 months-T(1), T(2,) T(3,) T(4)) using the Loe index. The evaluations were performed blindly by a single, calibrated examiner and were followed by prophylaxis and orientation regarding oral hygiene. The prevalence of nickel allergy was determined by the patch test 9 months after the beginning of treatment and occurred in 16 individuals (17.2%). Two groups were then established: the allergic group (AG, n = 16) and the age-paired nonallergic control group (NAG, n = 16). Data were analyzed using the Mann-Whitney U-test and Friedman's analysis of variance (ANOVA) tests (P < or = .05). Significant differences were present between groups at the T(3) and T(4) evaluations for the LOE index (P = .045 and .009), with allergic individuals showing higher mean values than nonallergic individuals (hyperplasia, change in color, and bleeding). No significant differences were found in the intragroup evaluations between the four evaluations (P > .05). The results suggest a cumulative effect from nickel throughout orthodontic treatment associated with clinically significant periodontal abnormalities in allergic individuals over time.