title: Influence of bleaching and desensitizing gel on bond strength of orthodontic brackets.
abstract: OBJECTIVE
  The objective of this study was to assess, in vitro, the influence of bleaching gel and the use of desensitizing agent over bond strength of ceramic brackets bonded to bovine enamel.
  
  
  METHODS
  One hundred bovine incisors were selected and randomly divided into five groups (n = 20): Group 1, control group (without bleaching); Group 2, bleached with 35% hydrogen peroxide; Group 3, bleached with 35% hydrogen peroxide (three applications, 15 minutes each) and desensitizing agent applied for 10 minutes; Group 4, bleached with 35% hydrogen peroxide for 40 minutes; Group 5, bleached with 35% hydrogen peroxide for 40 minutes with desensitizing agent applied for 10 minutes. Brackets were bonded 7 days after bleaching and submitted to shear bond strength test after 24 hours at a compression rate of 1 mm/minute. After fracture, the adhesive remnant index (ARI) was assessed under stereoscopic at 40 x magnification. Shear strength data (MPa) were submitted to one-way ANOVA and Tukey's test with significance level set at 5%.
  
  
  RESULTS
  Group 5 (29.33 MPa) showed significantly higher bond strength than Group 1 (19.19 MPa), Group 2 (20.59 MPa) and Group 4 (23.25 MPa), but with no difference in comparison to Group 3. There was no significant difference among the other groups. The adhesive remnant index showed predominance of score 3, that is, all resin remained adhered to enamel for all groups.
  
  
  CONCLUSIONS
  Bleaching with 35% hydrogen peroxide with calcium associated with desensitizing agent application produced higher bond strength values of brackets bonded to bovine enamel.
authors.affiliation: Centro Universitário Hermínio Ometto, Araras, São Paulo, Brazil.
authors.forename: Fernanda Alves Rodrigues
authors.initials: FA
authors.lastname: Britto
authors.affiliation: Department of Orthodontics, Centro Universitário Hermínio Ometto, Araras, São Paulo, Brazil.
authors.forename: Adriana Simoni
authors.initials: AS
authors.lastname: Lucato
authors.affiliation: Department of Orthodontics, Centro Universitário Hermínio Ometto, Araras, São Paulo, Brazil.
authors.forename: Heloisa Cristina
authors.initials: HC
authors.lastname: Valdrighi
authors.affiliation: Department of Orthodontics, Centro Universitário Hermínio Ometto, Araras, São Paulo, Brazil.
authors.forename: Sílvia Amélia Scudeler
authors.initials: SA
authors.lastname: Vedovello
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000268:Adhesiveness; D000818:Animals; D002118:Calcium / Q000737:chemistry; D002417:Cattle; D002516:Ceramics / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003743:Dental Enamel / Q000648:ultrastructure; D003764:Dental Materials / Q000737:chemistry; D003799:Dental Stress Analysis / Q000295:instrumentation; D057133:Dentin Desensitizing Agents / Q000737:chemistry*; D005782:Gels; D006861:Hydrogen Peroxide / Q000737:chemistry; D016910:Orthodontic Brackets; D011897:Random Allocation; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D058205:Tooth Bleaching Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D057133:Dentin Desensitizing Agents; D005782:Gels; D019279:Resin Cements; D058205:Tooth Bleaching Agents; C477790:Transbond XT; C516047:Transbond XT Light Cure Adhesive Primer; D014867:Water; D006861:Hydrogen Peroxide; D002118:Calcium