title: Peroxide penetration from the pulp chamber to the external root surface after internal bleaching.
abstract: OBJECTIVE
  To quantify the amount of peroxide penetration from the pulp chamber to the external surface of teeth during the walking bleaching technique.
  
  
  METHODS
  Seventy-two bovine lateral incisors were randomly divided over five experimental groups and one control (n = 12 per group): (1) 35% hydrogen peroxide (HP); (2) 35% carbamide peroxide (CP); (3) sodium perborate (SP); (4) (HP+SP); (5) (CP+SP) and (6) Control (CG), deionized water. All groups were treated according to the walking bleach technique. After 7 days at 37 degrees C in an acetate buffer solution, 100 microl violet leukocrystal coloring and 50 microl peroxidase was added, producing a blue stain that could be measured in a spectrophotometer and then converted into peroxide microg/ml.
  
  
  RESULTS
  G5 exhibited the greatest penetration, while G2 and G3 produced the lowest values. All bleaching agents penetrated from the pulp chamber to the external root surface. There was a direct correlation between the presence of oxidative agents and penetration potential. Sodium perborate in distilled water was less oxidative and appeared to be the least aggressive bleaching agent.
authors: Department of Endodontics, São Paulo State University, Araraquara, SP, Brazil.
authors: Renato Miotto
authors: RM
authors: Palo
authors: Marcia Carneiro
authors: MC
authors: Valera
authors: Samira Esteves Afonso
authors: SE
authors: Camargo
authors: Carlos Henrique Ribeiro
authors: CH
authors: Camargo
authors: Paula Elaine
authors: PE
authors: Cardoso
authors: Maria Nadir Gasparoto
authors: MN
authors: Mancini
authors: Cornelis H
authors: CH
authors: Pameijer
mesh_terms: D000134:Acid Etching, Dental; D000818:Animals; D001881:Borates / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000077463:Carbamide Peroxide; D002417:Cattle; D003739:Dental Cementum / Q000378:metabolism; D003745:Dental Enamel Permeability; D003806:Dentin Permeability; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D006861:Hydrogen Peroxide / Q000008:administration & dosage / Q000493:pharmacokinetics*; D016877:Oxidants / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010545:Peroxides / Q000008:administration & dosage / Q000493:pharmacokinetics*; D011897:Random Allocation; D014073:Tooth Bleaching / Q000379:methods*; D019237:Tooth Cervix / Q000378:metabolism*; D019553:Tooth, Nonvital; D014508:Urea / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics
chemical_list: D001881:Borates; D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide; C027707:sodium perborate