title: Tensile bond strength to primary dentin after different etching times.
abstract: OBJECTIVE
  The purpose of this study was to assess in vitro the effect of etching time on tensile bond strength to primary dentin.
  
  
  METHODS
  Forty crowns of sound primary molars were embedded in acrylic resin (N=40). Dentin was exposed in the buccal surfaces, and the specimens were randomly assigned into 4 groups (N=10), according to the etching time with 35% phosphoric acid gel: G1=7 seconds; G2=10 seconds; G3=15 seconds; G4=20 seconds. A 3-mm diameter bonding site was demarcated, the adhesive system was applied, and resin composite cones were built up. After 24 hours, tensile bond strength tests were performed. Data were submitted to statistical analysis using one-way analysis of variance and the Tukey test.
  
  
  RESULTS
  Means (+/-SD) were (MPa): (1) G1=10.04 (+/-3.30); (2) G2=7.78 (+/-4,49); (3) G3=8.78 (+/-2.96); (4) G4=7.60 (+/-1.91).
  
  
  CONCLUSIONS
  Although no statistically significant difference among the times used was found, the 7-second etching time promoted the highest bond strength mean and can be used in primary dentin. Additionally, this lower etching time reduces chair time, which is a significant benefit when treating children.
authors.affiliation: Department of Pediatric Clinics, Preventive and Social Dentistry, School of Dentistry of Ribeirão Preto, University of São Paulo, São Paulo, Brazil. carolptorres@hotmail.com
authors.forename: Carolina Paes
authors.initials: CP
authors.lastname: Torres
authors.forename: Michelle Alexandra
authors.initials: MA
authors.lastname: Chinelatti
authors.forename: Jaciara Miranda
authors.initials: JM
authors.lastname: Gomes-Silva
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Borsatto
authors.forename: Regina Guenka
authors.initials: RG
authors.lastname: Palma-Dibb
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins; D001840:Dental Bonding; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis; D003804:Dentin; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents; D006801:Humans; D008963:Molar; D010756:Phosphoric Acids; D019279:Resin Cements; D013718:Tensile Strength; D013997:Time Factors; D014094:Tooth, Deciduous
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D010756:Phosphoric Acids; D019279:Resin Cements; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; C030242:phosphoric acid