title: Resin bonding of metal brackets to glazed zirconia with a porcelain primer.
abstract: OBJECTIVE
  The aims of this study were to compare the shear bond strength between orthodontic metal brackets and glazed zirconia using different types of primer before applying resin cement and to determine which primer was more effective.
  
  
  METHODS
  Zirconia blocks were milled and embedded in acrylic resin and randomly assigned to one of four groups: nonglazed zirconia with sandblasting and zirconia primer (NZ); glazed zirconia with sandblasting, etching, and zirconia primer (GZ); glazed zirconia with sandblasting, etching, and porcelain primer (GP); and glazed zirconia with sandblasting, etching, zirconia primer, and porcelain primer (GZP). A stainless steel metal bracket was bonded to each target surface with resin cement, and all specimens underwent thermal cycling. The shear bond strength of the specimens was measured by a universal testing machine. A scanning electron microscope, three-dimensional optical surface-profiler, and stereoscopic microscope were used to image the zirconia surfaces. The data were analyzed with one-way analyses of variance and the Fisher exact test.
  
  
  RESULTS
  Group GZ showed significantly lower shear bond strength than did the other groups. No statistically significant differences were found among groups NZ, GP, and GZP. All specimens in group GZ showed adhesive failure between the zirconia and resin cement. In groups NZ and GP, bonding failed at the interface between the resin cement and bracket base or showed complex adhesive and cohesive failure.
  
  
  CONCLUSIONS
  Porcelain primer is the more appropriate choice for bonding a metal bracket to the surface of a full-contour glazed zirconia crown with resin cement.
authors.affiliation: Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan, Korea. ; Department and Research Institute of Dental Biomaterials and Bioengineering, BK21 PLUS Project, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Jung-Hwan
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Orthodontics, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Milim
authors.initials: M
authors.lastname: Lee
authors.affiliation: Department and Research Institute of Dental Biomaterials and Bioengineering, BK21 PLUS Project, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Kyoung-Nam
authors.initials: KN
authors.lastname: Kim
authors.affiliation: Department of Orthodontics, College of Dentistry, Yonsei University, Seoul, Korea. ; The Institute of Cranio-Facial Deformity, College of Dentistry, Yonsei University, Seoul, Korea.
authors.forename: Chung-Ju
authors.initials: CJ
authors.lastname: Hwang
keywords: Adhesive; Bracket bonding; Glazed zirconia; Porcelain primer