title: Evaluation of the bond strength between a composite resin and enamel submitted to bleaching treatment and etched with Er:YAG laser.
abstract: BACKGROUND
  The use of laser irradiation for dental surface treatment may increase tooth-composite bond strength. Its use on bleached teeth may decrease the waiting time between bleaching and restorative procedures.
  
  
  OBJECTIVE
  This study aimed to evaluate the bond strength between a composite resin and bovine enamel bleached with 35% hydrogen peroxide and etched with Er:YAG laser.
  
  
  METHODS
  Thirty bovine teeth were randomly divided into six groups (n = 5): G1, unbleached and restored 24 h after storage in artificial saliva, etching with 35% phosphoric acid (PA) (control); G2, unbleached and restored 24 h after storage in artificial saliva, etching with Er:YAG laser and 35% PA; G3, bleached and restored immediately afterward, etching with 35% PA; G4, bleached and restored 24 h after bleaching, etching with 35% PA; G5, bleached and restored immediately afterward, etching with Er:YAG and 35% PA laser; G6, bleached and restored 24 h after bleaching, etching with Er:YAG laser and 35% PA. Bond strength was quantitatively evaluated by microtensile test (1.0 mm/min). Data were submitted to statistical analysis using ANOVA and Tukey tests (α = 0.05).
  
  
  RESULTS
  Bond strength values (MPa) were G1, 26.17 ± 4.44; G2, 28.87 ± 3.94; G3, 17.25 ± 4.58; G4, 21.93 ± 5.02; G5, 16.69 ± 2.31; and G6, 29.06 ± 8.31. There was no statistically significant difference among groups G1, G2, and G6 (p = 0.119), which presented higher bond strength than group G4, followed by groups G3 and G5.
  
  
  CONCLUSIONS
  Er:YAG irradiation of bleached surfaces may favor bonding procedures when performed 24 h after bleaching.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry of São Paulo, University of São Paulo, São Paulo, SP, Brazil. adnlago@usp.br
authors.forename: Andréa Dias Neves
authors.initials: AD
authors.lastname: Lago
authors.forename: Patricia M
authors.initials: PM
authors.lastname: de Freitas
authors.forename: Narciso Garone
authors.initials: NG
authors.lastname: Netto
mesh_terms: D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000528:radiation effects*; D001840:Dental Bonding; D003743:Dental Enamel / Q000528:radiation effects*; D058250:Dental Restoration Repair; D053844:Lasers, Solid-State; D014073:Tooth Bleaching; D058205:Tooth Bleaching Agents; D019246:Tooth Preparation
chemical_list: D003188:Composite Resins; D058205:Tooth Bleaching Agents