title: Effect of operating air pressure on tribochemical silica-coating.
abstract: OBJECTIVE
  Alumina and zirconia are inert to conventional etching and need to be initially conditioned with, for example, silicatization. The aim of the present study was to evaluate the effect of operating air pressure of tribochemical silica-coating method on the shear bond strength of composite resin to ceramic substrates.
  
  
  METHODS
  Alumina (Procera Alumina, Nobel Biocare) and zirconia (LAVA; 3M ESPE and Procera Zirconia; Nobel Biocare) were airborne particle silica-coated (CoJet; 3M ESPE) using selected, clinically available air pressures of 150, 220, 300, and 450 kPa. The surfaces were silanized with silane coupling agent (ESPE Sil; 3M ESPE) and coated with adhesive resin (3M Multipurpose resin; 3M ESPE). Particulate filler resin composite (Z250; 3M ESPE) stubs (diameter 3.6 mm, height 4.0 mm) were added onto ceramics and light-cured for 40 s. The test specimens (n=18/group) were thermocycled (6000 x 5-55 degrees C) and shear bond strengths were measured with a cross-head speed of 1.0 mm/min. Fracture surfaces were examined with SEM, and an elemental analysis (EDS) was carried out to determine silica content on the substrate surface.
  
  
  RESULTS
  The highest bond strengths were obtained with the highest pressures. ANOVA showed significant differences in bond strength between the ceramics (p<0.05) and between the specimens treated at various air pressures (p<0.05).
  
  
  CONCLUSIONS
  Clinically, the operating air pressure of silicatization may have a significant effect on bond strength to non-etchable ceramics.
authors.affiliation: Department of Prosthetic Dentistry and Biomaterials Science, Institute of Dentistry, University of Turku, Turku, Finland. viliina@dnainternet.net
authors.forename: Timo T
authors.initials: TT
authors.lastname: Heikkinen
authors.forename: Lippo V J
authors.initials: LV
authors.lastname: Lassila
authors.forename: Jukka P
authors.initials: JP
authors.lastname: Matinlinna
authors.forename: Pekka K
authors.initials: PK
authors.lastname: Vallittu
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000399:Air Pressure; D000537:Aluminum Oxide / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D011140:Polyurethanes / Q000737:chemistry*; D033081:Shear Strength; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes; D012821:Silanes; D012822:Silicon Dioxide; D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide