title: Surface characterization of zirconia dental implants.
abstract: OBJECTIVE
  The aim of the study was to characterize the chemical composition, microstructure and roughness of two commercially available zirconia dental implants (WhiteSky and Zit-Z).
  
  
  METHODS
  The chemical composition of the cervical collar and threaded root parts of the implants (n=2) were studied by XPS and HV-EDX. LV-SEM was used for morphological assessment, Raman microanalysis for microstructural characterization and optical profilometry for surface roughness measurements. XRD, HV-EDX and Raman microanalysis of bulk regions (longitudinal sections) were used as reference.
  
  
  RESULTS
  XPS showed the presence of C, O, Zr and Y (collar) plus Al (root) at implant surfaces. More C (10-26at%) and a lower Al/Zr ratio were found in WhiteSky (1.05 vs 1.26 in Zit-Z). Zr, Y and Al were detected in single, fully oxidized states. The same elements, plus Hf, were identified by HV-EDX at bulk and surface regions, with a Al/Zr ratio higher in WhiteSky (0.17 vs 0.09 in Zit-Z). Na, K and Cl contaminants were traced at implant root parts by both methods. XRD analysis of cross-sectioned specimens revealed the presence of monoclinic and tetragonal zirconia along with cubic yttria phases. Raman microanalysis showed that the monoclinic zirconia volume fraction was higher at root surfaces than the collar. No monoclinic phase was found at bulk regions. Significantly higher Sa and Sq values were recorded in WhiteSky than Zit-Z, whereas Zit-Z showed higher Rt value.
  
  
  CONCLUSIONS
  The differences found between the implants in the extent of carbon contamination, residual alumina content, tetragonal to monoclinic ZrO(2) phase transformation and 3D-roughness parameters may contribute to a substantial differentiation in the cellular and tissue response.
authors.affiliation: Department of Biomaterials, University of Athens School of Dentistry, 2 Thivon Str-Goudi, Athens, Greece.
authors.forename: S
authors.initials: S
authors.lastname: Zinelis
authors.forename: A
authors.initials: A
authors.lastname: Thomas
authors.forename: K
authors.initials: K
authors.lastname: Syres
authors.forename: N
authors.initials: N
authors.lastname: Silikas
authors.forename: G
authors.initials: G
authors.lastname: Eliades
mesh_terms: D000704:Analysis of Variance; D018360:Crystallography, X-Ray; D015921:Dental Implants; D003776:Dental Porcelain / Q000737:chemistry*; D021621:Imaging, Three-Dimensional; D008855:Microscopy, Electron, Scanning; D056951:Photoelectron Spectroscopy; D013052:Spectrometry, X-Ray Emission; D013059:Spectrum Analysis, Raman; D018709:Statistics, Nonparametric; D013499:Surface Properties; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D015921:Dental Implants; C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D015019:Yttrium; D015040:Zirconium