title: Ex vivo evaluation of the effectiveness of bleaching agents on the shade alteration of blood-stained teeth.
abstract: OBJECTIVE
  To evaluate ex vivo effectiveness of the three formulations of bleaching materials for intracoronal bleaching of root filled teeth using the walking bleach technique.
  
  
  METHODS
  Extracted premolar teeth were stained artificially with human blood. After biomechanical preparation, the root canals were filled and a 3-mm thick intermediate base of zinc phosphate cement was placed at the level of the cementoenamel junction. The teeth were divided into four groups (n = 12): C (control, without bleaching material), A1 (sodium perborate + distilled water), A2 (sodium perborate + 10% carbamide peroxide) and A3 (sodium perborate + 35% carbamide peroxide). The bleaching materials were changed at 7 and 14 days. Evaluation of shade was undertaken with aid of the VITA Easyshadetrade mark (DeltaE*ab) and was performed after tooth staining and at 7, 14 and 21 days after bleaching, based on the CIELAB system. Data were analysed by anova for repeated measurements, Tukey and Dunnett tests (alpha = 0.05).
  
  
  RESULTS
  The Tukey test revealed that group A1 (10.58 +/- 4.83 DeltaE*ab) was statistically different from the others (A2, 19.57 +/- 4.72 DeltaE*ab and A3, 17.58 +/- 3.33 DeltaE*ab), which were not different from each other. At 7 days: A1 was significantly different from A2; at 14 and 21 days: A2 and A3 were significantly better than A1; the Dunnett test revealed that the control group was different from A1, A2 and A3 at all periods (P < 0.05).
  
  
  CONCLUSIONS
  Sodium perborate associated with both 10% and 35% carbamide peroxide was more effective than when associated with distilled water.
authors.affiliation: Department of Restorative Dentistry, São José dos Campos School of Dentistry, São Paulo State University, São Paulo, Brazil. karenyui@fosjc.unesp.br
authors.forename: K C K
authors.initials: KC
authors.lastname: Yui
authors.forename: J R
authors.initials: JR
authors.lastname: Rodrigues
authors.forename: M N G
authors.initials: MN
authors.lastname: Mancini
authors.forename: I
authors.initials: I
authors.lastname: Balducci
authors.forename: S E P
authors.initials: SE
authors.lastname: Gonçalves
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid; D001801:Blood Stains; D001881:Borates / Q000627:therapeutic use; D000077463:Carbamide Peroxide; D003786:Dental Pulp Cavity / Q000187:drug effects*; D003806:Dentin Permeability / Q000187:drug effects; D004338:Drug Combinations; D006801:Humans; D006861:Hydrogen Peroxide / Q000627:therapeutic use; D066298:In Vitro Techniques; D008137:Longitudinal Studies; D010545:Peroxides / Q000627:therapeutic use; D012387:Root Canal Filling Materials / Q000009:adverse effects; D012389:Root Canal Obturation / Q000379:methods; D012390:Root Canal Therapy / Q000379:methods*; D018709:Statistics, Nonparametric; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D014075:Tooth Discoloration / Q000188:drug therapy* / Q000209:etiology; D019553:Tooth, Nonvital / Q000628:therapy; D014508:Urea / Q000031:analogs & derivatives / Q000627:therapeutic use
chemical_list: D001881:Borates; D004338:Drug Combinations; D010545:Peroxides; D012387:Root Canal Filling Materials; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide; C027707:sodium perborate