title: Bleaching agents increase metalloproteinases-mediated collagen degradation in dentin.
abstract: BACKGROUND
  Tooth bleaching is based on hydrogen peroxide application. The Objective of this study was to determine whether dental bleaching agents affect metalloproteinases-mediated dentin collagen degradation.
  
  
  METHODS
  Human dentin specimens were subjected to different treatments: (1) untreated dentin; (2) demineralization by 37% phosphoric acid (PA); (3) demineralization by 37% PA, followed by application of Single Bond (SB); (4) 2 immersions of 7 days each in a nonvital bleaching agent, followed by PA; (5) 2 immersions of 7 days each in nonvital bleaching, followed by PA and SB application; (6) 3 immersions by using in-office bleaching gel for 20 minutes; (7) 3 immersions by using in-office bleaching gel for 20 minutes plus activation with a light source; and (8) immersion in home bleaching gel for 8 hours per day during 3 weeks. Specimens were stored in artificial saliva. C-terminal telopeptide determinations (radioimmunoassay) were performed after 24 hours, 1 week, and 4 weeks.
  
  
  RESULTS
  Bleaching agents increased collagen degradation, but C-terminal telopeptide of type I collagen (ICTP) values were higher when dentin was PA-demineralized. Nonvital bleaching plus PA promoted the highest collagenolytic activity, which was reduced after SB infiltration. Halogen light application did not influence ICTP values. At 24 hours, home bleaching exhibited high collagenolytic activity, which decreased up to 4 weeks. After 4 weeks of storage, all bleaching procedures showed similar values of collagen degradation, which were not different from those of PA-demineralized and resin-infiltrated dentin.
  
  
  CONCLUSIONS
  All tested bleaching agents increase matrix metalloproteinases-mediated collagen degradation in dentin. This effect was not completely reverted after 4 weeks. Home bleaching induced the highest collagen degradation.
authors.affiliation: Department of Dental Materials, School of Dentistry, University of Granada, Campus de Cartuja, Granada, Spain. toledano@ugr.es
authors.forename: Manuel
authors.initials: M
authors.lastname: Toledano
authors.forename: Monica
authors.initials: M
authors.lastname: Yamauti
authors.forename: Estrella
authors.initials: E
authors.lastname: Osorio
authors.forename: Raquel
authors.initials: R
authors.lastname: Osorio
mesh_terms: D017438:Bisphenol A-Glycidyl Methacrylate / Q000494:pharmacology; D000077463:Carbamide Peroxide; D003094:Collagen / Q000187:drug effects / Q000378:metabolism*; D024042:Collagen Type I / Q000032:analysis; D003804:Dentin / Q000187:drug effects*; D017220:Dentin-Bonding Agents / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007101:Immersion; D008027:Light; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D010455:Peptides / Q000032:analysis; D010545:Peroxides / Q000494:pharmacology; D010756:Phosphoric Acids / Q000494:pharmacology; D012464:Saliva, Artificial / Q000737:chemistry; D013997:Time Factors; D058205:Tooth Bleaching Agents / Q000494:pharmacology*; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D024042:Collagen Type I; D017220:Dentin-Bonding Agents; D010455:Peptides; D010545:Peroxides; D010756:Phosphoric Acids; D012464:Saliva, Artificial; C511238:Single Bond Plus; D058205:Tooth Bleaching Agents; C052929:collagen type I trimeric cross-linked peptide; D000077463:Carbamide Peroxide; D017438:Bisphenol A-Glycidyl Methacrylate; D014508:Urea; D003094:Collagen; D006861:Hydrogen Peroxide; C030242:phosphoric acid; D020782:Matrix Metalloproteinases