title: Development of a novel surface modification for improved bonding to zirconia.
abstract: OBJECTIVE
  This report presents a novel pretreatment technique, whereby the zirconia surface is converted to a more reactive zirconium oxyfluoride, enabling improved chemical bonding to other dental substrates via conventional silanation approaches.
  
  
  METHODS
  The study leverages a novel gas-phase fluorination process that creates a thin oxyfluoride conversion layer on the surface of zirconia, making it more reactive for conventional adhesive bonding techniques. Zirconia specimens, polished and roughened, were pretreated and composite cylinders bonded using conventional adhesive techniques. All specimens were subjected to a force at a crosshead speed of 0.5mm/min in an electro-mechanical testing device. Single-factor analysis of variance (ANOVA) at a 5% confidence level was performed for the bonding strength data. Optical microscopy and scanning electron microscopy (SEM) were used to evaluate and quantify failure surfaces.
  
  
  RESULTS
  Shear bond strengths were analyzed using single-factor ANOVA (p<0.05). Mechanical testing results revealed that fluorinated zirconia specimens (both rough and polished) displayed the highest shear bond strengths as compared to other commercially available treatments. X-ray photoelectron spectroscopy analysis helped determine that this novel pretreatment created a more reactive, 2-4nm thick oxyfluoride conversion layer with approximate stoichiometry, ZrO(3)F(4).
  
  
  CONCLUSIONS
  Simple shear bond mechanical tests demonstrated that a fluorination pre-treatment is a viable method to chemically modify zirconia to produce a reactive surface for adhesive bonding.
authors.affiliation: Center for Materials and Electronic Technologies, RTI International, Durham, NC 27709, USA. jpiascik@rti.org
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Piascik
authors.forename: Scott D
authors.initials: SD
authors.lastname: Wolter
authors.forename: Brian R
authors.initials: BR
authors.lastname: Stoner
mesh_terms: D000268:Adhesiveness; D000537:Aluminum Oxide / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry; D045662:Dental Etching / Q000379:methods*; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing; D003799:Dental Stress Analysis / Q000295:instrumentation; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005461:Fluorine / Q000737:chemistry*; D054879:Halogenation; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D019279:Resin Cements; D033081:Shear Strength; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C474035:Filtek Supreme; C076808:Monobond S; D010087:Oxides; C483701:Rely X Unicem; D019279:Resin Cements; D012821:Silanes; D014867:Water; D005461:Fluorine; D012822:Silicon Dioxide; C014559:fluorine monoxide; D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide