Effects of Long-Term Fixed Orthodontic Treatment on Salivary Nickel and Chromium Levels: a 1-Year Prospective Cohort Study

Abstract

Effect of long-term orthodontic treatment on salivary nickel and chromium has not been quite assessed except in few retrospective studies with controversial results. The aim of this prospective study was to measure salivary levels of these ions during 1 year of orthodontic treatment. Saliva samples were collected from 20 orthodontic patients, before treatment (control) and 6 and 12 months later. Nickel and chromium concentrations were determined using atomic absorption spectrophotometry. Data were analyzed using one- and two-way repeated-measures ANOVA, Bonferroni, Friedman (α = 0.05), and Wilcoxon signed-ranks tests (α = 0.016). Average nickel level changed from 9.75 ± 5.02 to 10.37 ± 6.94 and then to 8.32 ± 4.36 μg/L in 1 year. Average chromium concentration changed from 3.86 ± 1.34 to 4.6 ± 6.11 and then to 2.04 ± 1.66 μg/L. Alterations in nickel values were not statistically significant [P = 0.468 (ANOVA)], but fluctuations in chromium levels were [P = 0.021 (Friedman)]. The decrease in chromium concentration after 12 months was significant compared to the control [P = 0.004 (Wilcoxon)]. Although slightly increased after 6 months, the concentration of both ions dropped to levels slightly lower than the control groups after 12 months.

Urinary Nickel Ion Evaluation of Adolescents during the Initial Period of Orthodontic Fixed Treatment

“…However, the orthodontic devices would permanently interact with the chemical and physical stimulations of oral physiological environment, such as variable pH values, dietary intake, temperature, dental plaque, mechanical fatigue and so on [1][2][3][4][5][6][7][8][9][10] , thus a question arises about potential biosafety considerations for such a therapy.…”

“…Fixed appliances might be the major source of exposure to nickel in the orthodontic patients. While nickel is not only an essential, but also a allergenic, mutagenic, carcinogenic and cytotoxic trace element, which could cause contact dermatitis, immunodeficiency, cancer, and even birth defects 1,[8][9][10][11][15][16][17] .…”

Environmental and occupational exposure to chromium in Iran: A systematic review

“…Amini, year of data collection not reported [15] 20 patents with fixed orthodontics (12 female and 8 male)…”

Effects of the initial stage of active fixed orthodontic treatment and sex on dental plaque accumulation: A preliminary prospective cohort study

“…Of the 25 patients, 20%, 20%, 24%, 28%, and 8% were in age groups [18][19][20], [21][22][23], [24][25][26], [27][28][29], and [30][31][32], respectively. The plaque index doubled, from a baseline value of 19.60 ± 8.02 to 45.00 ± 16.44 after the leveling stage (Tables 1 and 2).…”