title: A double-blind randomized clinical trial of two carbamide peroxide tooth bleaching agents: 2-year follow-up.
abstract: OBJECTIVE
  This double-blind randomized clinical trial aimed to evaluate the whitening effect of two at-home tooth bleaching agents and the effect of dietary habits after 2 years. The patients' view about bleaching longevity was also investigated.
  
  
  METHODS
  Ninety-two subjects with mean shade of C1 or darker for the six maxillary anterior teeth were randomized into two groups (n=46) according to the carbamide peroxide (CP) concentration: 10% (CP10) or 16% (CP16). The treatment was performed using the whitening agent in a tray for 2h/day during 3 weeks. Shade evaluations were done with a shade guide and a spectrophotometer at baseline, 1-month, 6-month, 1-year and 2-year post-bleaching.
  
  
  RESULTS
  Eighty-one (88%) of the original 92 subjects enrolled in the study were recalled at 2-year follow-up and, the tooth shade remained significantly lighter than at baseline, in both treatment groups, considering the tooth shade median values (p<0.001) or the color parameters: L*a* (p<0.001) for CP10 and, L*b* for CP16 group (p<0.001). Subjects from CP10 and CP16 reported a consumption of beverage and food stains as high as at 6-month and 1-year recalls and, more than 66% of the participants from each group reported a tooth shade relapse from mild to moderate (p=0.6).
  
  
  CONCLUSIONS
  At 2-year post-bleaching, tooth shade remained lighter than at baseline for both CP concentrations tested. Tooth shade relapse associated to increasing of a* and b* color parameters were observed for both groups when compared to the end of the treatment (CEP # 37/05).
authors: Department of Operative Dentistry, Federal University of Paraíba, João Pessoa, PB, Brazil.
authors: S S
authors: SS
authors: Meireles
authors: I S
authors: IS
authors: Santos
authors: A Della
authors: AD
authors: Bona
authors: F F
authors: FF
authors: Demarco
mesh_terms: D000077463:Carbamide Peroxide; D016009:Chi-Square Distribution; D003481:Cuspid; D004032:Diet; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005500:Follow-Up Studies; D006801:Humans; D007180:Incisor; D017060:Patient Satisfaction; D010545:Peroxides / Q000008:administration & dosage; D012008:Recurrence; D013053:Spectrophotometry; D018709:Statistics, Nonparametric; D058205:Tooth Bleaching Agents / Q000008:administration & dosage; D014075:Tooth Discoloration / Q000628:therapy; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives*
chemical_list: D010545:Peroxides; D058205:Tooth Bleaching Agents; D000077463:Carbamide Peroxide; D014508:Urea