title: Efficacy of tooth bleaching with the prior application of a desensitizing agent.
abstract: OBJECTIVE
  In the present study, we evaluated the efficacy of bleaching on enamel and opposite dentin surfaces using 35% hydrogen peroxide (HP) with the prior application of a desensitizing agent.
  
  
  METHODS
  Thirty bovine dental fragments, with thicknesses of 1 mm enamel and 1.75 mm dentin, were stained in a solution of black tea. The fragments were randomly divided into three groups (n = 10) according to the following protocols: (a) 2% neutral fluoride + bleaching; (b) desensitizing agent + bleaching; and (c) without desensitizer + bleaching. The bleaching efficacy was evaluated four times: after staining with tea (baseline) and after each of the 3 weeks of bleaching, by means of the CIE Lab method using a reflectance spectrophotometer. The data coordinate L* was evaluated by an analysis of repeated measures with PROC MIXED and Tukey-Kramer's test. The ΔE values were subjected to anova and Tukey's test (α = 0.05).
  
  
  RESULTS
  The 35% HP treatment showed greater efficacy on deep dentin after removal of the enamel stains, with increasing means during all times in all treatments.
  
  
  CONCLUSIONS
  The use of a desensitizing agent prior to the bleaching session did not affect the mechanism of action of 35% HP with regard to tooth depth.
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas - UNiCAMP, Piracicaba, São Paulo, Brazil.
authors.forename: Juliana
authors.initials: J
authors.lastname: do Carmo Públio
authors.forename: Maria B F
authors.initials: MB
authors.lastname: D'Arce
authors.forename: Gláucia M B
authors.initials: GM
authors.lastname: Ambrosano
authors.forename: Flávio H B
authors.initials: FH
authors.lastname: Aguiar
authors.forename: José R
authors.initials: JR
authors.lastname: Lovadino
authors.forename: Luís A M S
authors.initials: LA
authors.lastname: Paulillo
authors.forename: Débora A N L
authors.initials: DA
authors.lastname: Lima
mesh_terms: D000818:Animals; D002417:Cattle; D003116:Color; D003743:Dental Enamel / Q000187:drug effects* / Q000648:ultrastructure; D003804:Dentin / Q000187:drug effects*; D057133:Dentin Desensitizing Agents / Q000627:therapeutic use*; D005459:Fluorides / Q000627:therapeutic use; D006861:Hydrogen Peroxide / Q000627:therapeutic use*; D008855:Microscopy, Electron, Scanning; D009566:Nitrates / Q000627:therapeutic use; D017680:Potassium Compounds / Q000627:therapeutic use; D011897:Random Allocation; D012969:Sodium Fluoride / Q000627:therapeutic use; D013053:Spectrophotometry / Q000379:methods; D013662:Tea; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D058205:Tooth Bleaching Agents / Q000627:therapeutic use*; D014075:Tooth Discoloration / Q000188:drug therapy
chemical_list: D057133:Dentin Desensitizing Agents; D009566:Nitrates; D017680:Potassium Compounds; D013662:Tea; D058205:Tooth Bleaching Agents; D012969:Sodium Fluoride; D006861:Hydrogen Peroxide; D005459:Fluorides; C023844:potassium nitrate
keywords: dentin sensitivity; fluoride; hydrogen peroxide; tooth bleaching; tooth discoloration