title: XPS analysis of the surface of leucite-reinforced feldspathic ceramics.
abstract: OBJECTIVE
  The bond of a silane-coupling agent to a ceramic surface is expected to be influenced by the composition and chemical state of the ceramic surface. The purpose of this study was to determine the variation in the composition and the chemical states of the surfaces of a range of leucite-reinforced feldspathic (LRF) ceramics using X-ray photoelectron spectroscopy (XPS).
  
  
  METHODS
  Five LRF ceramic discs (IPS Empress,Optec HSP,VMK 68, Mirage, and a modified Mirage) were produced and polished to a 1 microm finish. A further nine discs of the modified Mirage were produced. The discs were stored for 48h in a vacuum oven at 110 degrees C to remove absorbed water. The surfaces of these discs were analysed by XPS. Survey scans at 30 degrees take-off angle were taken and surface composition (in at%) was calculated from the narrow scans for Si 2p, O 1s, Al 2p, Mg 2s, K 2p, Na 1s, Ca 2p and N 1s.
  
  
  RESULTS
  Atomic concentration of elements (after exclusion of C) for the five LRF ceramics were in the range: O, 45.0-51.6%; Si, 26.7-35.6%; Al, 6.3-9.7%; Mg, 4.9-8.8%; K, 0.5-2.2%; N, 0.9-2.9% and less than 1% of Na and Ca. The shapes of the O 1s and Si 2p narrow scan core lines of the five LRF ceramics were virtually identical.
  
  
  CONCLUSIONS
  All five LRF ceramics were found to have a silica-rich surface layer due to a reduction in K and Na relative to the bulk composition. Both the composition and chemical states of the surfaces for the five LRF ceramics were very similar.
authors: Centre for Biomaterials and Tissue Engineering, University of Sheffield, Sheffield, UK.
authors: T
authors: T
authors: Hooshmand
authors: R
authors: R
authors: Daw
authors: R
authors: R
authors: van Noort
authors: R D
authors: RD
authors: Short
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D001840:Dental Bonding; D003776:Dental Porcelain / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods; D017680:Potassium Compounds / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties
chemical_list: D000538:Aluminum Silicates; C075815:IPS-Empress ceramic; C080875:Mirage; D017680:Potassium Compounds; D012821:Silanes; C111131:VMK 68; D003776:Dental Porcelain; C016447:feldspar; C073101:Optec; C078519:leucite