title: Influence of ultraviolet photofunctionalization on the surface characteristics of zirconia-based dental implant materials.
abstract: OBJECTIVE
  To examine the effect of ultraviolet light (UV) treatment on the surface characteristics of two acid-etched zirconia-based dental implant materials.
  
  
  METHODS
  Discs of two zirconia-based materials (Zr1 and Zr2) with smooth (m) and roughened (r) surfaces were treated by UV light for 15min. The surface topography was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface elemental composition of all samples was determined by X-ray photoelectron spectroscopy (XPS), the crystalline property by X-ray diffraction (XRD) and the hydrophilic status by contact angle (CA) measurements of a water droplet.
  
  
  RESULTS
  SEM and AFM revealed quantitative and qualitative differences between the roughened and smooth surfaces. UV treatment did not induce any topographic changes of the tested surfaces (p>0.05). All UV-treated samples showed a significant surface elemental content change with a decrease of carbon by 43-81%, an increase of oxygen by 19-45%, and an increase of zirconia by 9-41%. Upon UV treatment, a 19-25% increase of the crystalline monoclinic phase was observed on surfaces of material Zr1, whereas a slight increase on the smooth Zr2 surface (+3%) and a decrease on the roughened Zr2 surface by 20% was observed. For all samples, the hydrophilic status changed significantly from hydrophobic to hydrophilic by UV treatment (p<0.0001). The average contact angles were between 56.4° and 69° before and 2.5° and 14.1° after UV-light treatment.
  
  
  CONCLUSIONS
  UV treatment altered the physicochemical properties of the two zirconia implant surfaces investigated. The mechanism by which such changes are induced requires further investigation.
authors.affiliation: Department of Prosthodontics, School of Dentistry, Albert-Ludwigs University of Freiburg, Germany. Electronic address: ttuna@ukaachen.de.
authors.forename: Taskin
authors.initials: T
authors.lastname: Tuna
authors.affiliation: Department of Oral Biotechnology, School of Dentistry, Albert-Ludwigs University of Freiburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Wein
authors.affiliation: Department of Prosthodontics, School of Dentistry, Albert-Ludwigs University of Freiburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Swain
authors.affiliation: Institute for Dental Materials and Engineering, University Hospital for Dental Medicine, University of Basel, Switzerland.
authors.forename: Jens
authors.initials: J
authors.lastname: Fischer
authors.affiliation: Department of Prosthodontics, School of Dentistry, Albert-Ludwigs University of Freiburg, Germany.
authors.forename: Wael
authors.initials: W
authors.lastname: Att
mesh_terms: D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D055595:Mechanical Phenomena; D008855:Microscopy, Electron, Scanning; D056951:Photoelectron Spectroscopy; D013499:Surface Properties; D014466:Ultraviolet Rays; D014961:X-Ray Diffraction; D015040:Zirconium / Q000737:chemistry*
chemical_list: D015921:Dental Implants; D003764:Dental Materials; D015040:Zirconium; C028541:zirconium oxide
keywords: Dental implant; Photofunctionalization; Physical property; Surface characteristics; Surface chemistry; Ultraviolet; Zirconia