title: 3D-characterization of the veneer-zirconia interface using FIB nano-tomography.
abstract: OBJECTIVE
  The phenomena occurring during zirconia frameworks veneering process are not yet fully understood. In particular the study of zirconia behavior at the interface with the veneer remains a challenge. However this interface has been reported to act on residual stress in the veneering ceramic, which plays a significant role in clinical failures such as chipping. The objective of this study was thus to investigate the veneer-zirconia interface using a recent 3D-analysis tool and to confront these observations to residual stress measurements in the veneering ceramic.
  
  
  METHODS
  Two cross-sectioned bilayered disc samples (veneer on zirconia), exhibiting different residual stress profiles in the veneering ceramic, were investigated using 2D and 3D imaging (respectively Scanning Electron Microscopy (SEM) and Focused Ion Beam nanotomography (FIB-nt), associated with chemical analysis by Energy Dispersive X-ray Spectroscopy (EDS).
  
  
  RESULTS
  The observations did not reveal any structural change in the bulk of zirconia layer of both samples. However the presence of structural alterations and sub-surface microcracks were highlighted in the first micrometer of zirconia surface, exclusively for the sample exhibiting interior tensile stress in the veneering ceramic. No interdiffusion phenomena were observed.
  
  
  CONCLUSIONS
  FIB nanotomography was proven to be a powerful technique to study the veneer-zirconia interface. The determination of the origin and the nature of zirconia alterations need to be further studied. The results of the present study support the hypothesis that zirconia surface property changes could be involved in the development of tensile stress in the veneering ceramic, increasing the risk of chipping.
authors.affiliation: Department of Fixed Prosthodontics, Institute of Dentistry, University of Liege Hospital (ULg CHU), Liège 4020, Belgium. a.mainjot@chu.ulg.ac.be
authors.forename: Amélie K
authors.initials: AK
authors.lastname: Mainjot
authors.forename: Thierry
authors.initials: T
authors.lastname: Douillard
authors.forename: Laurent
authors.initials: L
authors.lastname: Gremillard
authors.forename: Michaël J
authors.initials: MJ
authors.lastname: Sadoun
authors.forename: Jérôme
authors.initials: J
authors.lastname: Chevalier
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D003799:Dental Stress Analysis; D003801:Dental Veneers; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008855:Microscopy, Electron, Scanning / Q000379:methods; D013052:Spectrometry, X-Ray Emission / Q000379:methods; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry*
chemical_list: D015040:Zirconium