title: A clinical study of the effect of pellicle on the degradation of 10% carbamide peroxide within the first hour.
abstract: OBJECTIVE
  The purpose of this study was to determine the degradation of 10% carbamide peroxide within the first hour of use and the effect of pellicle on the degradation of carbamide peroxide in vivo.
  
  
  METHODS
  Fifteen subjects were assigned to wear nightguard trays filled with bleaching gel for 0.5, 2.5, 5.0, 10.0, 20.0, 40.0, and 60.0 minutes under 2 conditions: (1) subjects did not receive a prophylaxis before each bleaching treatment (pellicle was assumed to be present on the tooth surface); and (2) subjects received prophylaxis to remove pellicle from the tooth surface. At each evaluation time, 3 types of sample were collected: (1) a "grab sample," a sample of gel taken with a spatula from the reservoir of the tray on the maxillary right central incisor; (2) the remaining gel from the tray; and (3) the remaining gel scraped from the teeth. The collected gel samples were analyzed for the amount of peroxide using the United States Pharmacopeia-accepted method. Subjects were asked not to swallow the saliva during treatment but to expectorate into a beaker. The collected saliva was analyzed to determine the amount of peroxide. This sample represented the approximate amount of peroxide that subject would ingest during treatment.
  
  
  RESULTS
  Pellicle did not affect the degradation of carbamide peroxide for the teeth or grab samples. The degradation of carbamide peroxide was exponential, except during the first 5 minutes, when the degradation rate was much higher. The saliva collected from subjects during use of the bleaching tray revealed an average of 2.1 mg of carbamide peroxide for 1 hour of bleaching treatment.
  
  
  CONCLUSIONS
  The degradation rate is not affected by the removal of the pellicle.
authors.affiliation: Indiana University, School of Dentistry, Indianapolis 46202, USA.
authors.forename: P
authors.initials: P
authors.lastname: Wattanapayungkul
authors.forename: B A
authors.initials: BA
authors.lastname: Matis
authors.forename: M A
authors.initials: MA
authors.lastname: Cochran
authors.forename: B K
authors.initials: BK
authors.lastname: Moore
mesh_terms: D000704:Analysis of Variance; D000077463:Carbamide Peroxide; D003741:Dental Deposits / Q000737:chemistry; D044622:Dental Pellicle; D004338:Drug Combinations; D006801:Humans; D010545:Peroxides / Q000737:chemistry*; D012463:Saliva / Q000737:chemistry*; D013997:Time Factors; D014073:Tooth Bleaching; D014508:Urea / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D004338:Drug Combinations; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea