In vivo study on the release of nickel, chromium, and zinc in saliva and serum from patients treated with fixed orthodontic appliances

Abstract

Background: Fixed orthodontic appliances can release metal ions such as nickel, chromium, and
zinc into saliva and blood, which can cause contact dermatitis, hypersensitivity, and cytotoxicity.
This study was undertaken to assess the release of nickel, chromium, and zinc in saliva and serum
of patients undergoing fixed orthodontic treatment.
Materials and Methods: This in vivo study was conducted on 80 participants with an age range
of 15–40 years. Thirty were included as controls and 50 participants were treated with fixed
orthodontic appliances. Saliva and blood samples were collected at five different periods, before
insertion of fixed orthodontic appliance and at 1 week, 3 months, 1 year, and 1.5 years after insertion
of appliance, respectively. The metal ion content in the samples were analyzed by atomic absorption
spectrophotometry. Mean levels of nickel, chromium, and zinc in saliva and serum were compared
between groups using independent sample t‑test and before and after results using paired t‑test.
P < 0.05 was considered as statistically significant.
Results: At the end of 1.5 years, the mean salivary levels of nickel, chromium, and zinc in controls
were 5.02 ppb, 1.27 ppb, and 10.24 ppb, respectively, as compared to 67 ppb, 30.8 ppb, and
164.7 ppb at the end of 1.5 years. This was statistically significant with P < 0.001. A significant
increase in the metal ion levels were seen in participants with before and after insertion of
appliance (P < 0.001).
Conclusion: Orthodontic appliances do release considerable amounts of metal ions such as
nickel, chromium, and zinc in saliva and serum. However, it was within permissible levels and did
not reach toxic levels.
Key Words: Chromium, nickel, orthodontic appliances, saliva, zinc