title: Surface fluorination of zirconia: adhesive bond strength comparison to commercial primers.
abstract: OBJECTIVE
  This study evaluated contact angle and shear bond strength of three commercial zirconia primers and compared them to a recently developed fluorination pre-treatment. Earlier investigations reported that plasma fluorinated zirconia modifies the chemical bonding structure creating a more reactive surface.
  
  
  METHODS
  Yttria-stabilized zirconia (LAVA, 3M ESPE) plates were highly polished using 3μm diamond paste (R(a) ∼200nm) prior to pretreatments. After primer and fluorination treatment, contact angles were measured to quantify surface hydrophobicity before and after ethanol clean. Additionally, simple shear bond tests were performed to measure the adhesion strength to a composite resin.
  
  
  RESULTS
  Plasma fluorination produced the lowest contact angle (7.8°) and the highest shear bond strength (37.3MPa) suggesting this pretreatment facilitates a more "chemically" active surface for adhesive bonding.
  
  
  CONCLUSIONS
  It is hypothesized that plasma fluorination increase hydroxylation at the surface, making it more reactive, thus allowing for covalent bonding between zirconia surface and resin cement. A strong correlation was observed between contact angle and adhesion strength for all specimens; a relationship which may help understand the frequency and modes of failures, clinically. It is also believed that this surface treatment can increase long-term viability of zirconia restorations over other adhesive techniques.
authors.affiliation: Center for Materials & Electronic Technologies, RTI International, Research Triangle Park, NC, USA. jpiascik@rti.org
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Piascik
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Swift
authors.forename: Krista
authors.initials: K
authors.lastname: Braswell
authors.forename: Brian R
authors.initials: BR
authors.lastname: Stoner
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding / Q000379:methods*; D003764:Dental Materials; D005465:Fluorocarbon Polymers / Q000737:chemistry*; D054879:Halogenation; D008422:Materials Testing; D058626:Plasma Gases; D033081:Shear Strength; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D005465:Fluorocarbon Polymers; D058626:Plasma Gases; D015040:Zirconium; C028541:zirconium oxide