title: Fracture resistance of yttrium oxide partially-stabilized zirconia all-ceramic bridges after veneering and mechanical fatigue testing.
abstract: OBJECTIVE
  Yttria-stabilized zirconia (Y-TZP) ceramic is a high-performance material with excellent mechanical properties suitable for fixed partial dentures. The purpose of this study was to evaluate after fatigue testing, the effect of heat-treatment and veneering on the fracture resistance of frameworks manufactured using sintered and subsequently hot isostatic pressed yttrium oxide partially-stabilized zirconia (Denzir).
  
  
  METHODS
  The specimens were subjected to dynamic loading in water. Thereafter, using a universal testing machine, the fracture resistance of three-unit fixed partial dentures was determined; (i) of the frameworks as delivered after machining, (ii) after the frameworks had been subjected to heat-treatment similar to veneering with a glass-ceramic (Eris) or a feldspar-based ceramic (Vita D) and (iii) after the frameworks had been veneered with these ceramics. In addition, the fracture resistance of frameworks as delivered after machining not subjected to dynamic loading in water was determined.
  
  
  RESULTS
  Cyclic loading in water did not significantly (p>0.05) affect the fracture resistance. The load necessary to fracture the frameworks as delivered after machining was significantly (p<0.001) higher than for the heat-treated and veneered specimens. No significant difference was seen between the specimens veneered with Eris and those veneered with Vita D (p>0.05). For all but three specimens the fractures were located in the loading point and through one of the connectors.
  
  
  CONCLUSIONS
  Heat-treatment and veneering reduce fracture resistance of hot isostatic pressed zirconia. Nevertheless, the results obtained indicate that it is an interesting material for potential in all-ceramic restorations.
authors.affiliation: Department of Odontology, Faculty of Medicine, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Sundh
authors.forename: Margareta
authors.initials: M
authors.lastname: Molin
authors.forename: Göran
authors.initials: G
authors.lastname: Sjögren
mesh_terms: D002516:Ceramics; D017076:Computer-Aided Design; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003801:Dental Veneers; D003779:Denture Design; D003830:Denture, Partial, Fixed; D006358:Hot Temperature; D018709:Statistics, Nonparametric; D015019:Yttrium; D015040:Zirconium
chemical_list: C500744:Eris ceramic; C502262:vita veneering ceramic D; C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D015019:Yttrium; D015040:Zirconium