Nickel and chromium ions levels in saliva of patients with fixed orthodontic appliances

Abstract EN

Objective : The aim of this study was to test the hypothesis that there is no difference in salivary metal ion content between subjects with fixed orthodontic appliances and their same-gender sister or brother without any orthodontic appliance.

Materials and methods : Fifty orthodontic patients were included in this study.

The first group consisted of 25 patients (14 female, 11 male) with fixed appliances placed in their upper and lower arches.

The second group consisted of 25 patients (13 female, 12 male) with a fixed appliance placed only in the upper arch.

In order to limit the effects of dietary and hygiene habits on salivary metal ion concentration, a same-gender brother or sister (total of 50 subjects) was selected as a control (25 female, 25 male) who were not undergoing orthodontic treatment.

Four samples of stimulated saliva were collected from each patient before insertion of the fixed appliance, 1 month after insertion of the appliance, 2 months after insertion of the appliance and 6 months after insertion of the appliance.

The 4 samples of saliva were collected from each control patient at the same time intervals as for the fixed-appliance groups.

Approximately 5 ml of saliva was collected from each subject.

Saliva samples were analyzed for nickel, chromium, by electrothermal atomic absorption spectrophotometry.

The detection limit of the method for sample solutions was 1 ng / ml.

Statistical analysis was performed by nonparametric tests (Mann-Whitney U and Wilcoxon W).

The Wilcoxon matched pairs signed ranks used to test differences between samples before and after insertion of the orthodontic appliances.

A Kruskal Wallis 1-way analysis of variance was used to test differences in nickel and chromium concentration among the 3 test groups.

A Kruskal Wallis 1-way analysis of variance (ANOVA) was used to test differences in nickel and chromium concentrations among the 3 test groups.

Results : The mean salivary nickel (Ni) content in subjects with and without a fixed orthodontic appliance was 16.8 ± 12.2 ng / ml and 10.3 ± 11.7 ng / ml, respectively.

A statistically significant difference (P < 0.041) was found between the two groups.

The mean salivary chromium (Cr) ion level recorded was 2.4 ± 1.8 ng / ml in the study group and 2.1 ± 1.6 ng / ml in the control group.

The difference, however, was statistically insignificant.

Conclusion : Nickel and chromium ion concentrations increased immediately after placement of the appliance in the mouth for all study groups.

There were no significant differences in the nickel, chromium levels released by the three groups of appliances at all study periods.

Within the limits of this in vivo study, it can be concluded that the presence of fixed orthodontic appliances leads to an increased concentration of metal ions in salivary secretions.