title: Silica-based nano-coating on zirconia surfaces using reactive magnetron sputtering: effect on chemical adhesion of resin cements.
abstract: OBJECTIVE
  To compare the effect of silica (Si)-based nano-coating deposited by reactive magnetron sputtering (RMP) with that of conventional surface conditioning using metal/zirconia primer alone or after air-particle abrasion on the adhesion of resin cements to zirconia ceramic.
  
  
  METHODS
  Two hundred forty zirconia ceramic blocks (Cercon) were sintered, finished with 1200- grit SiC paper under water cooling, and cleaned ultrasonically in distilled water for 10 min. The blocks (4.5 mm x 3.5 mm x 4.5 mm) were randomly divided into 24 groups (n = 10) according to 3 testing parameters: a) resin cements (Multilink, Panavia F, RelyX U100), b) surface conditioning (no conditioning as control group; Metal/Zirconia Primer; air abrasion + Metal/Zirconia Primer; Si-based nanofilm + Monobond s); c) aging (no aging vs thermocycling at 5°C to 55°C, 6000 cycles). The nanofilm was deposited by direct current using argon/oxygen plasma (8:1 in flux) on the zirconia surface. Resin cements were bonded to zirconia surfaces using polyethylene molds. The shear bond strength (SBS) test was performed using a universal testing machine (1 mm/min), and after debonding, the substrate and adherent surfaces were analyzed using optical and scanning electron microscopes to categorize the failure types. The data were statistically evaluated using 3-way ANOVA and Tukey's test (5%).
  
  
  RESULTS
  Resin cement type (p < 0.05), surface conditioning method (p < 0.05), and aging condition (p < 0.05) had a significant effect on the bond strength results. Interactions were also significant (p < 0.05). In the nonaged condition, while control groups presented the lowest results with all cements (0 to 5.2 MPa), the airabraded group in combination with RelyX U100 resulted in the highest SBS (21.8 ± 6.7 MPa). After aging, the SBS results decreased in the air-abraded groups for all cements (4.54 to 9.44 MPa) and showed no statistical significance compared to the Si-based nanocoated groups (4.24 to 6.44 MPa). After air-abrasion and primer application, only Panavia F and RelyX U100 cements showed exclusively mixed failures, but after nanofilm coating and silanization, all cements showed exclusively mixed failures with and without aging.
  
  
  CONCLUSIONS
  Chemical adhesion of the resin cements tested to zirconia was similar after silica-based nanofilm deposition and air abrasion followed by primer application.
authors.affiliation: Department of of Prosthodontics and Dental Materials, Sao Paulo State University, Sao Jose dos Campos, Brazil.
authors.forename: José Renato
authors.initials: JR
authors.lastname: Queiroz
authors.forename: Marcos
authors.initials: M
authors.lastname: Massi
authors.forename: Lafayette
authors.initials: L
authors.lastname: Nogueira
authors.forename: Argemiro Soares
authors.initials: AS
authors.lastname: Sobrinho
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Bottino
authors.forename: Mutlu
authors.initials: M
authors.lastname: Ozcan
mesh_terms: D020906:Air Abrasion, Dental; D020099:Coated Materials, Biocompatible; D001840:Dental Bonding; D003776:Dental Porcelain; D003799:Dental Stress Analysis; D017220:Dentin-Bonding Agents; D006358:Hot Temperature; D008422:Materials Testing; D053758:Nanoparticles; D011897:Random Allocation; D019279:Resin Cements; D012822:Silicon Dioxide; D013499:Surface Properties; D014867:Water; D015019:Yttrium; D015040:Zirconium
chemical_list: D020099:Coated Materials, Biocompatible; D017220:Dentin-Bonding Agents; C438843:Panavia-Fluoro; C483701:Rely X Unicem; D019279:Resin Cements; C502351:multilink adhesive system; C499362:yttria stabilized tetragonal zirconia; D014867:Water; D003776:Dental Porcelain; D015019:Yttrium; D012822:Silicon Dioxide; D015040:Zirconium