A double-blind randomized controlled clinical trial of 10 percent versus 16 percent carbamide peroxide tooth-bleaching agents: one-year follow-up

J Am Dent Assoc. 2009 Sep;140(9):1109-17. doi: 10.14219/jada.archive.2009.0337.


Background: The use of high-concentration tooth-bleaching agents has been associated with increased longevity of the whitening effect. The authors conducted a randomized controlled clinical trial to evaluate the longevity of the whitening effect at one year of two at-home tooth-bleaching agents.

Methods: The authors randomly assigned 92 participants with a mean shade of C1 or darker for six maxillary anterior teeth into two equal-sized groups according to carbamide peroxide concentration: 10 percent (CP10) or 16 percent (CP16). Treatment involved the use of a whitening agent in a tray for two hours daily for three weeks. The authors evaluated tooth shade with a shade guide and a spectrophotometer at baseline and one week, six months and one year after bleaching. Participants in both groups answered questions about their dietary and oral hygiene behaviors.

Results: At the one-year recall appointment, the teeth in both groups remained significantly lighter than at baseline. At this time, participants from the CP10 and CP16 groups consumed staining beverages and foods at a level as high as at the six-month recall appointment, and this consumption level was not statistically significant between groups (P > .5).

Conclusions: One year after bleaching, both treatment groups had the same median tooth shade, which remained lighter than at baseline.

Clinical implications: Higher carbamide peroxide concentration does not increase the longevity of the whitening effect of at-home tooth-bleaching agents.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Beverages
  • Carbamide Peroxide
  • Color
  • Dentin Sensitivity / chemically induced
  • Double-Blind Method
  • Drug Combinations
  • Feeding Behavior
  • Female
  • Follow-Up Studies
  • Food
  • Humans
  • Male
  • Middle Aged
  • Oral Hygiene
  • Oxidants / administration & dosage*
  • Peroxides / administration & dosage*
  • Spectrophotometry
  • Time Factors
  • Tooth / pathology
  • Tooth Bleaching / methods*
  • Tooth Discoloration / therapy
  • Urea / administration & dosage
  • Urea / analogs & derivatives*
  • Young Adult


  • Drug Combinations
  • Oxidants
  • Peroxides
  • Carbamide Peroxide
  • Urea