title: Cytotoxicity, genotoxicity, and metal release in patients with fixed orthodontic appliances: a longitudinal in-vivo study.
abstract: BACKGROUND
  Treatment with fixed orthodontic appliances in the corrosive environment of the oral cavity warrants in-vivo investigations of biocompatibility.
  
  
  METHODS
  Eighteen control and 28 treated subjects were evaluated longitudinally. Four combinations of brackets and archwires were tested. Buccal mucosa cell samples were collected before treatment, and 3 and 6 months after appliance placement. The cells were processed for cytotoxicity, genotoxicity, and nickel and chromium contents.
  
  
  RESULTS
  In the treatment group, buccal mucosa cell viability values were 8.1% at pretreatment, and 6.4% and 4.5% at 3 and 6 months, respectively. The composite score, a calculated DNA damage value, decreased from 125.6 to 98.8 at 6 months. Nickel cellular content increased from 0.52 to 0.68 and 0.78 ng per milliliter, and chromium increased from 0.31 to 0.41 and 0.78 ng per milliliter at 3 and 6 months, respectively. Compared with the control group, the treated subjects showed significant differences for DNA damage and chromium content at 3 months only.
  
  
  CONCLUSIONS
  Fixed orthodontic appliances decreased cellular viability, induced DNA damage, and increased the nickel and chromium contents of the buccal mucosa cells. Compared to the control group, these changes were not evident at 6 months, possibly indicating tolerance for or repair of the cells and the DNA.
authors: Department of Orthodontics, Oral and Dental Research Division, National Research Center, Giza, Egypt.
authors: Hend Salah
authors: HS
authors: Hafez
authors: Essam Mohamed Nassef
authors: EM
authors: Selim
authors: Faten Hussein
authors: FH
authors: Kamel Eid
authors: Wael Attia
authors: WA
authors: Tawfik
authors: Emad A
authors: EA
authors: Al-Ashkar
authors: Yehya Ahmed
authors: YA
authors: Mostafa
mesh_terms: D000293:Adolescent; D002470:Cell Survival / Q000187:drug effects*; D002857:Chromium / Q000032:analysis; D003343:Corrosion; D004249:DNA Damage; D003722:Dental Alloys / Q000633:toxicity*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008670:Metals / Q000032:analysis; D009061:Mouth Mucosa / Q000737:chemistry / Q000166:cytology / Q000187:drug effects*; D009532:Nickel / Q000032:analysis / Q000633:toxicity; D009967:Orthodontic Appliances / Q000009:adverse effects*; D013193:Stainless Steel / Q000633:toxicity; D018709:Statistics, Nonparametric; D014025:Titanium / Q000633:toxicity; D055815:Young Adult
chemical_list: D003722:Dental Alloys; D008670:Metals; D002857:Chromium; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium