title: Evaluation of the genotoxic effects of fixed appliances on oral mucosal cells and the relationship to nickel and chromium concentrations: an in-vivo study.
abstract: BACKGROUND
  The release of metal ions from fixed orthodontic appliances is a source of concern. The aim of this study was to evaluate genotoxic damage in the oral mucosal cells of patients wearing fixed appliance, and the nickel and chromium ion contents in these cells.
  
  
  METHODS
  Twenty patients undergoing orthodontic treatment formed the experimental group, and 20 untreated subjects comprised the control group. Oral mucosal smears were collected at 2 times: at debonding and 30 days after debonding. The smears were stained with Papanicolaou stain and studied under a light microscope to evaluate the presence of micronuclei. Inductively coupled plasma-mass spectrometry was used to quantify the presence of metal ions. The data were subjected to the Mann-Whitney U test and the Spearman rank correlation test.
  
  
  RESULTS
  The mean micronuclei frequency was significantly higher in the treated group than in the control group at debonding; the difference was smaller and not statistically significant 30 days after debonding. The nickel and chromium ion contents in the experimental group were not significantly higher than in the control group. No correlation could be established between micronuclei frequency and metal ion content.
  
  
  CONCLUSIONS
  Nickel and chromium alloys of orthodontic appliances emit metal ions in sufficient quantities to induce localized genotoxic effects, but these changes revert on removal of the appliances.
authors: Department of Orthodontics, Faculty of Dental Sciences, Sir Ramachandra Medical College, Chennai, India.
authors: Madhumitha
authors: M
authors: Natarajan
authors: Sridevi
authors: S
authors: Padmanabhan
authors: Arun
authors: A
authors: Chitharanjan
authors: Malathi
authors: M
authors: Narasimhan
mesh_terms: D000293:Adolescent; D002857:Chromium / Q000032:analysis; D003343:Corrosion; D004249:DNA Damage; D003722:Dental Alloys / Q000737:chemistry / Q000633:toxicity*; D006801:Humans; D015162:Micronucleus Tests; D009061:Mouth Mucosa / Q000737:chemistry / Q000166:cytology / Q000187:drug effects*; D009532:Nickel / Q000032:analysis / Q000737:chemistry / Q000633:toxicity; D009967:Orthodontic Appliances / Q000009:adverse effects*; D013193:Stainless Steel / Q000737:chemistry / Q000633:toxicity; D018709:Statistics, Nonparametric; D014025:Titanium / Q000737:chemistry / Q000633:toxicity; D055815:Young Adult
chemical_list: D003722:Dental Alloys; D002857:Chromium; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium