title: New mechanical retention method for resin and gold alloy bonding.
abstract: OBJECTIVE
  The purpose of this study was to improve adhesion between dental adhesive resins and 14K gold alloy by creating a sponge-like structure on the alloy surface which enhanced mechanical bonding.
  
  
  METHODS
  The internal oxidation particles of Cu oxides precipitated on a 14K gold alloy surface after high-temperature oxidation at 800 degrees C in air were removed by pickling with an acid solution to create a sponge-like structure on the alloy surface. A PMMA resin containing 4-META as an adhesive monomer and a self-cured resin without 4-META were used to examine the effects of mechanical and chemical factors on bond strength. A thiophosphate-type metal primer (M-Primer II) was used in combination with 4-META resin to strengthen the chemical bonding of 4-META resin to the porous alloy surface. The surfaces of the alloy specimen treated by oxidation, pickling, and bonding with 4-META resin were analyzed using an electron probe X-ray micro-analyzer.
  
  
  RESULTS
  SEM observation showed many resin tags on the resin side of the bond structure after removal of the gold alloy matrix with aqua regia. The bond strength of 4-META resin to the porous alloy surface was 38+/-3 (mean+/-SD) MPa whereas that to a flat alloy surface with the same composition was 19+/-1 MPa. The bond strength of a self-cured resin without 4-META to the porous alloy surface was 24+/-2 MPa.
  
  
  CONCLUSIONS
  A high bond strength was obtained when 4-META resin was bonded to the porous 14K gold alloy surface treated with M-Primer II.
authors.affiliation: Department of Dental Materials Science, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293, Japan. ohno@hoku-iryo-u.ac.jp
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ohno
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Endo
authors.forename: Masanori
authors.initials: M
authors.lastname: Hashimoto
mesh_terms: D000180:Acrylic Resins; D001840:Dental Bonding / Q000379:methods*; D004577:Electron Probe Microanalysis; D006047:Gold Alloys; D008689:Methacrylates; D010084:Oxidation-Reduction; D019279:Resin Cements; D013499:Surface Properties; D013718:Tensile Strength; D013864:Thioglycolates
chemical_list: D000180:Acrylic Resins; D006047:Gold Alloys; D008689:Methacrylates; D019279:Resin Cements; D013864:Thioglycolates; C100646:Metal Primer; C031172:4-META resin