title: XRD2 micro-diffraction analysis of the interface between Y-TZP and veneering porcelain: role of application methods.
abstract: OBJECTIVE
  The metastability of the tetragonal crystal structure of yttria partial stabilized zirconia polycrystalline (Y-TZP) ceramics is a basis of concern for dental restorations. Reactions between the porcelain and the Y-TZP framework may result in a reduction of the stability of the zirconia and interface bonding caused by a transformation from tetragonal to monoclinic crystalline structure during veneering.
  
  
  METHODS
  XRD(2) micro-diffraction measurements were carried out on tapered veneered cross-sections of the interface area to generate locally resolved information of the phase content in this region. To get a high intensity X-ray beam for short measurement times a focussing polycapillary with a spot size of app. 50 microm was used to evaluate the porcelain zirconia interface.
  
  
  RESULTS
  Under almost all conditions the phase composition of zirconia grains at the interface revealed both the monoclinic and tetragonal structure. These observations indicate that destabilization of the tetragonal phase of zirconia occurs at the interface during veneering with porcelain.
  
  
  CONCLUSIONS
  These results and their relevance to the long-term stability of the interface adhesion between zirconia and veneering porcelain as well as the tetragonal to monoclinic crystal transformations at the interface are discussed.
authors.affiliation: Research and Development Department VITA Zahnfabrik, Bad Saeckingen, Germany.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Tholey
authors.forename: Christoph
authors.initials: C
authors.lastname: Berthold
authors.forename: Michael V
authors.initials: MV
authors.lastname: Swain
authors.forename: Norbert
authors.initials: N
authors.lastname: Thiel
mesh_terms: D000537:Aluminum Oxide; D017076:Computer-Aided Design; D003460:Crystallization; D001840:Dental Bonding; D003776:Dental Porcelain / Q000737:chemistry*; D003801:Dental Veneers; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D044367:Phase Transition; D013499:Surface Properties; D014961:X-Ray Diffraction / Q000295:instrumentation / Q000379:methods*; D015019:Yttrium / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
chemical_list: C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; C070870:In-Ceram; D015019:Yttrium; D015040:Zirconium; D000537:Aluminum Oxide