title: Methacrylate bonding to zirconia by in situ silica nanoparticle surface deposition.
abstract: OBJECTIVE
  This study introduces an innovative method to enhance adhesion of methacrylate-based cements to yttria-stabilized zirconia (Y-TZP) by means of a silica-nanoparticle deposition process.
  
  
  METHODS
  Two alkoxide organic precursors, tetraethyl-orthosilicate (TEOS) and zirconium tert-butoxide (ZTB) were diluted in hexane at different concentrations in order to obtain several experimental materials to enhance deposition of a SiO(x) reactive layer to Y-TZP. This deposition was attained via sintering alkoxide precursors directly on pre-sintered zirconia (infiltration method—INF) or application on the surface of fully sintered zirconia (coating method—COA). Untreated specimens and a commercial tribochemical silica coating were also tested as controls and all the treated Y-TZP specimens were analyzed using SEM-EDX. Specimens were bonded using silane, adhesive and dual-cure luting cement and submitted to shear bond strength test after different water storage periods (24 h, 3-, 6- and 12-months).
  
  
  RESULTS
  SEM-EDX revealed Y-TZP surface covered by silica nanoclusters. The morphology of silica-covered Y-TZP surfaces was influenced by sintering method, employed to deposit nanoclusters. High bond strength (MPa) was observed when using COA method; highest TEOS percentage achieved the greatest bond strengths to Y-TZP surface (36.7±6.3 at 24 h). However, bonds stability was dependent on ZTB presence (32.9±9.7 at 3 months; 32.3±7.1 at 6 months). Regarding INF method, the highest and more stable resin-zirconia bond strength was attained when using experimental solutions containing TEOS and no ZTB. Both sintering methods tested in this study were able to achieve a bonding performance similar to that of classic tribochemical strategies.
  
  
  CONCLUSIONS
  This study demonstrates that it is possible to achieve a reliable and long-lasting bonding between yttria-stabilized zirconia ceramic and methacrylate-based cements when using this novel, simple, and cost-effective bonding approach.
authors.affiliation: Biomaterials Development and Control Center, School of Dentistry, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Aline
authors.initials: A
authors.lastname: Oliveira-Ogliari
authors.affiliation: Dental Materials Laboratory, School of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Fabrício M
authors.initials: FM
authors.lastname: Collares
authors.affiliation: School of Dentistry, Federal University of Ceará, Fortaleza, Brazil.
authors.forename: Victor P
authors.initials: VP
authors.lastname: Feitosa
authors.affiliation: Dental Biomaterials and Minimally Invasive Dentistry, Departamento de Odontología, Universidad CEU-Cardenal Herrera, Valencia, Spain. Electronic address: salvatore.sauro@uch.ceu.es.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Sauro
authors.affiliation: School of Materials Engineering, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Fabrício A
authors.initials: FA
authors.lastname: Ogliari
authors.affiliation: Biomaterials Development and Control Center, School of Dentistry, Federal University of Pelotas, Pelotas, Brazil.
authors.forename: Rafael R
authors.initials: RR
authors.lastname: Moraes
mesh_terms: D001840:Dental Bonding / Q000379:methods*; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D015019:Yttrium / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
chemical_list: D008689:Methacrylates; D015019:Yttrium; D012822:Silicon Dioxide; D015040:Zirconium; C028541:zirconium oxide; C091417:yttria
keywords: Biomaterials; Bonding; Ceramics; Silica-coating; Yttria-stabilized polycrystalline zirconia