title: Shear bond strength of a hot pressed Au-Pd-Pt alloy-porcelain dental composite.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effect of hot pressing on the shear bond strength of a Au-Pt-Pd alloy-porcelain composite.
  
  
  METHODS
  Several metal-porcelain composites specimens were produced by two different routes: conventional porcelain fused to metal (PFM) and hot pressing. In the latter case, porcelain was hot pressed onto a polished surface (PPPS) as well as a roughened one (PPRS). Bond strength of all metal-porcelain composites were assessed by the means of a shear test performed in a universal test machine (crosshead speed: 0.5 mm/min) until fracture. Interfaces of fractured specimens as well as undestroyed interface specimens were examined with optical microscope, stereomicroscope, Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS). The data were analyzed using one-way ANOVA followed by Tuckey's test (p<0.05).
  
  
  RESULTS
  Shear bond strength of conventional PFM specimens were in line with the upper range of literature data (83±14 MPa). Hot pressing proved to significantly increase bond strength between metal and porcelain (p<0.05). For both polished and roughened surface the shear bond strength values for hot pressed specimens were 120±16 MPa and 129±5 MPa, respectively, which represents an improvement of more than 50% relatively to a conventional PFM. Roughened surface did not have a significant effect on bond strength of hot pressed specimens (p>0.05).
  
  
  CONCLUSIONS
  This study shows that it is possible to significantly improve metal-porcelain bond strength by applying an overpressure during porcelain firing.
authors.affiliation: Center for Mechanical and Materials Technologies, University of Minho, Campus de Azurém, 4800-058 Guimarães, Portugal. brunohenriques@dem.uminho.pt
authors.forename: B
authors.initials: B
authors.lastname: Henriques
authors.forename: D
authors.initials: D
authors.lastname: Soares
authors.forename: F S
authors.initials: FS
authors.lastname: Silva
mesh_terms: D000497:Alloys / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D006358:Hot Temperature; D008422:Materials Testing; D010165:Palladium / Q000737:chemistry; D010984:Platinum / Q000737:chemistry; D011312:Pressure; D033081:Shear Strength
chemical_list: D000497:Alloys; D003776:Dental Porcelain; D010984:Platinum; D010165:Palladium; D006046:Gold