title: Effect of a metal primer on the adhesive interface between composite and lingual brackets.
abstract: OBJECTIVE
  To test the null hypothesis was that there is no difference in the shear strength of indirectly bonded lingual brackets with or without prior application of metal primer on their bases.
  
  
  METHODS
  Forty recently extracted human premolars were obtained and randomly divided into two groups of 20 each: group I (control), phosphoric acid and indirect bonding with Maximum Cure (Reliance Orthodontic Products, Itasca, IL, USA); and group II, application of metal primer (Metal Primer, Reliance Orthodontic Products) on bracket base prior to conditioning and indirect bonding. All products were used according to the manufacturer's instructions. A universal testing machine was used to apply a shear force directly onto the enamel- bracket interface at a speed of 1.0 mm/min.
  
  
  RESULTS
  Mean (SD) shear bond strength for group I was 12.87 (5.75) MPa and for the group II was 18.47 (8.48) MPa. The Student's t-test showed a significant difference (p = 0.0311) between the groups. The chi-square test for the adhesive remnant index (ARI) indicated that there was a significant difference (p = 0.2750).
  
  
  CONCLUSIONS
  The application of metal primer increased the adhesion of lingual brackets, and may be a promising procedure for clinical orthodontics.
authors.affiliation: Professor, Division of Orthodontics, Fluminense Federal University Nova Friburgo, Rio de Janeiro, Brazil, Phone: 552225287168, e-mail: juliocalneto@yahoo.com.br.
authors.forename: Julio Pedrae
authors.initials: JP
authors.lastname: Cal Neto
authors.affiliation: Professor, Division of Orthodontics, Fluminense Federal University, Nova Friburgo, Rio de Janeiro, Brazil.
authors.forename: José de Albuquerque
authors.initials: Jde A
authors.lastname: Calasans-Maia
authors.affiliation: Former Resident, Division of Orthodontics, Fluminense Federal University, Niterói, Rio de Janeiro, American Samoa.
authors.forename: Natalia Valli
authors.initials: NV
authors.lastname: de Almeida
authors.affiliation: Undergraduate Student, School of Dentistry, Fluminense Federal University, Nova Friburgo, Rio de Janeiro, Brazil.
authors.forename: Helen
authors.initials: H
authors.lastname: Rohen
authors.affiliation: Undergraduate Student, School of Dentistry, Fluminense Federal University, Nova Friburgo, Rio de Janeiro, Brazil.
authors.forename: Maria Angélica Galvão
authors.initials: MA
authors.lastname: Freire
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000268:Adhesiveness; D003188:Composite Resins / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods*; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D003722:Dental Alloys; D008689:Methacrylates; D010756:Phosphoric Acids; D019279:Resin Cements; C477790:Transbond XT; C087211:maximum cure; C100646:Metal Primer; C030242:phosphoric acid