title: Evaluation of genotoxicity and efficacy of at-home bleaching in smokers: a single-blind controlled clinical trial.
abstract: OBJECTIVE
  This single-blind controlled study evaluated the genotoxicity and efficacy of at-home bleaching in smokers and nonsmokers.
  
  
  METHODS
  We selected 60 patients with central incisors A2 or darker: 30 smokers (experimental group) and 30 nonsmokers (control group). The bleaching was carried out with 10% carbamide peroxide for three hours a day for three weeks. The color was evaluated using a shade guide, Vita Bleachedguide 3D-Master, at baseline, during bleaching (first, second, and third weeks), and one week and one month after bleaching. Smears were obtained with a moistened wooden spatula from marginal gingiva. All the cytologic smears were stained with Giemsa solution. From each slide, 1000 cells were examined under 40× magnification and where micronuclei (MN) were located, they were examined under 100× magnification. The change in shade guide units at the different assessment periods and the frequency of MN were subjected to a two-way repeated measures analysis of variance and Tukey test (α=0.05).
  
  
  RESULTS
  In both groups we detected a whitening of approximately 4 to 5 shade guide units, without color rebound after one month (p>0.05). The frequency of MN was significantly higher in the experimental group than in the control group, regardless of the bleaching treatment (p>0.001).
  
  
  CONCLUSIONS
  The efficacy of bleaching does not appear to be affected by the smoking habit. Additionally, at-home bleaching did not induce DNA damage to the gingival tissue during the bleaching period.
authors.forename: J L
authors.initials: JL
authors.lastname: de Geus
authors.forename: M
authors.initials: M
authors.lastname: Rezende
authors.forename: L S
authors.initials: LS
authors.lastname: Margraf
authors.forename: M C
authors.initials: MC
authors.lastname: Bortoluzzi
authors.forename: E
authors.initials: E
authors.lastname: Fernández
authors.forename: A D
authors.initials: AD
authors.lastname: Loguercio
authors.forename: A
authors.initials: A
authors.lastname: Reis
authors.forename: S
authors.initials: S
authors.lastname: Kossatz
mesh_terms: D000293:Adolescent; D000328:Adult; D000077463:Carbamide Peroxide; D004249:DNA Damage / Q000187:drug effects; D005260:Female; D005881:Gingiva / Q000187:drug effects; D006801:Humans; D008297:Male; D009152:Mutagenicity Tests; D010545:Peroxides / Q000008:administration & dosage / Q000627:therapeutic use* / Q000633:toxicity; D012648:Self Care / Q000009:adverse effects / Q000379:methods; D016037:Single-Blind Method; D012907:Smoking / Q000009:adverse effects*; D014073:Tooth Bleaching / Q000009:adverse effects / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000008:administration & dosage / Q000627:therapeutic use* / Q000633:toxicity; D014075:Tooth Discoloration / Q000188:drug therapy; D016896:Treatment Outcome; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use / Q000633:toxicity; D055815:Young Adult
chemical_list: D010545:Peroxides; D058205:Tooth Bleaching Agents; D000077463:Carbamide Peroxide; D014508:Urea