title: Thermo and mechanical cycling and veneering method do not influence Y-TZP core/veneer interface bond strength.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the influence of thermal and mechanical cycling and veneering technique on the shear bond strength of Y-TZP (yttrium oxide partially stabilized tetragonal zirconia polycrystal) core-veneer interfaces.
  
  
  METHODS
  Cylindrical Y-TZP specimens were veneered either by layering (n=20) or by pressing technique (n=20). A metal ceramic group (CoCr) was used as control (n=20). Ten specimens for each group were thermal and mechanical cycled and then all samples were subjected to shear bond strength in a universal testing machine with a 0.5mm/min crosshead speed. Mean shear bond strength (MPa) was analysed with a 2-way analysis of variance and Tukey's test (p<0.05). Failure mode was determined using stereomicroscopy and scanning electron microscopy (SEM).
  
  
  RESULTS
  Thermal and mechanical cycling had no influence on the shear bond strength for all groups. The CoCr group presented the highest bond strength value (p<0.05) (34.72 ± 7.05 MPa). There was no significant difference between Y-TZP veneered by layering (22.46 ± 2.08 MPa) or pressing (23.58 ± 2.1 MPa) technique. Failure modes were predominantly adhesive for CoCr group, and cohesive within veneer for Y-TZP groups.
  
  
  CONCLUSIONS
  Thermal and mechanical cycling, as well as the veneering technique does not affect Y-TZP core-veneer bond strength.
  
  
  CONCLUSIONS
  Different methods of veneering Y-TZP restorations would not influence the clinical performance of the core/veneer interfaces.
authors.affiliation: Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil. hvidotti@yahoo.com.br
authors.forename: Hugo Alberto
authors.initials: HA
authors.lastname: Vidotti
authors.forename: Jefferson Ricardo
authors.initials: JR
authors.lastname: Pereira
authors.forename: Elizeu
authors.initials: E
authors.lastname: Insaurralde
authors.forename: Ana Lúcia Pompéia Fraga
authors.initials: AL
authors.lastname: de Almeida
authors.forename: Accácio Lins
authors.initials: AL
authors.lastname: do Valle
mesh_terms: D000704:Analysis of Variance; D002516:Ceramics; D002858:Chromium Alloys; D003035:Cobalt; D001840:Dental Bonding; D003776:Dental Porcelain; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D003801:Dental Veneers; D006358:Hot Temperature; D008422:Materials Testing; D033081:Shear Strength; D015019:Yttrium / Q000008:administration & dosage; D015040:Zirconium / Q000008:administration & dosage
chemical_list: D002858:Chromium Alloys; C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D003035:Cobalt; D015019:Yttrium; C023506:Glass ceramics; D015040:Zirconium