Comparison Between Nickel and Chromium Levels in Serum and Urine in Patients Treated with Fixed Orthodontic Appliances: A Longitudinal Study

Objective: To compare levels of nickel and chromium in serum and urine in orthodontic patients treated with fixed orthodontic appliances. Material and Methods: Nickel and chromium ion concentration were measured in serum and urine of twenty patients (12 females and 8 males, aged 17-28 years old) who had fixed orthodontic treatment using Coupled Plasma-Atomic Emission Spectroscopy. The samples were taken before treatment (Baseline), two months, and six months later during treatment. Data were analyzed using repeated ANOVA, Bonferroni post-hoc test, and paired t-tests. The level of significance was set at 5%. Results: Average serum nickel level changed from 6.420 ppb to 6.855 ppb. Average serum chromium level changed from 5.305 ppb to 5.505 ppb in 6 months. Average urinary nickel level changed from 5.320 ppb to 5.610 ppb. Average urinary chromium level changed from 5.370 ppb to 5.520 ppb in 6 months. There was a statistically significant difference in serum (p<0.001) and urinary chromium (p=0.007) levels between observation times. Conclusion: Orthodontic treatment might raise both urinary and serum nickel levels, but the differences were not statistically significant; the alterations in chromium levels were not consistent; nickel levels were higher in serum than in urine; chromium levels were higher in urine than in serum.