title: Clinical effectiveness and tooth sensitivity associated with different bleaching times for a 10 percent carbamide peroxide gel.
abstract: BACKGROUND
  The daily application time for 10 percent carbamide peroxide (CP) typically is between four and eight hours. However, to the authors' knowledge, no investigators in clinical studies have compared different application times; this is the aim of this study.
  
  
  METHODS
  The authors recruited 60 patients and categorized each of them into one of four groups. All participants used 10 percent CP in a bleaching tray. The daily application times were 15 minutes, 30 minutes, one hour or eight hours. Participants bleached their teeth for 16 days and those who were not satisfied with the results extended the bleaching time until they were satisfied. Patients recorded their tooth sensitivity on a 0 to 4 scale. The authors measured the shade changes by using a digital spectrophotometer and shade guide. They performed appropriate statistical analysis of the data (α = .05).
  
  
  RESULTS
  Participants in the one- and eight-hour groups bleached their teeth for 18 and 16 days, respectively (P > .05), while statistically longer periods were required for participants in the other two groups (P < .001) to be satisfied with the results. Participants' tooth sensitivity ratings were similar for the 15-minute, 30-minute and one-hour application times (P > .05), and they were statistically lower than those for participants in the eight-hour group.
  
  
  CONCLUSIONS
  The eight-hour bleaching protocol yielded faster bleaching; however, participants experienced higher sensitivity levels. The one-hour group most closely approached the eight-hour group with regard to bleaching speed, while those in the one-hour group experienced lower sensitivity levels.
  
  
  CONCLUSIONS
  In this study, the difference in bleaching speed between the eight- and one-hour application times after 16 days was small, and the results showed less tooth sensitivity for patients in the one-hour group.
authors.affiliation: Restorative Dentistry, Federal University of Goiás, Goiânia, GO, Brazil.
authors.forename: Paula C
authors.initials: PC
authors.lastname: Cardoso
authors.forename: Alessandra
authors.initials: A
authors.lastname: Reis
authors.forename: Alessandro
authors.initials: A
authors.lastname: Loguercio
authors.forename: Luiz C C
authors.initials: LC
authors.lastname: Vieira
authors.forename: Luiz N
authors.initials: LN
authors.lastname: Baratieri
mesh_terms: D000293:Adolescent; D000328:Adult; D000077463:Carbamide Peroxide; D003116:Color; D003807:Dentin Sensitivity / Q000209:etiology*; D005260:Female; D005782:Gels; D006801:Humans; D007180:Incisor / Q000187:drug effects / Q000473:pathology; D008297:Male; D008437:Maxilla; D010147:Pain Measurement; D017060:Patient Satisfaction; D010545:Peroxides / Q000008:administration & dosage*; D016037:Single-Blind Method; D013053:Spectrophotometry; D013997:Time Factors; D014073:Tooth Bleaching / Q000295:instrumentation / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000008:administration & dosage*; D014075:Tooth Discoloration / Q000188:drug therapy / Q000473:pathology; D016896:Treatment Outcome; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives*; D055815:Young Adult
chemical_list: D005782:Gels; D010545:Peroxides; D058205:Tooth Bleaching Agents; D000077463:Carbamide Peroxide; D014508:Urea