title: Fracture Load Before and After Veneering Zirconia Posterior Fixed Dental Prostheses.
abstract: OBJECTIVE
  To evaluate the fracture load of 3-unit zirconia-based posterior fixed dental prostheses (FDPs) before and after veneering the frameworks.
  
  
  METHODS
  Forty standardized stainless-steel master dies were fabricated (height: 5 mm, convergence: 6º, chamfer: 1 mm) and randomly screwed in pairs onto metal bases. The bases were randomly divided into two groups (n = 20 each) according to the zirconia CAD/CAM system used for constructing 3-unit structures for FDPs: group 1 (L): Lava All-ceramic, group 2 (Z): IPS e.max ZirCAD. Half of the zirconia structures per group were randomly selected and veneered, while the remaining half was left unveneered. The specimens were luted in standard fashion onto the stainless steel master dies using conventional glass ionomer cement. All specimens were tested for fracture load (FL). Specimens were subjected to a three-point bending test until fracture by applying an axial compressive load at the central fossa of the pontics with a universal testing machine at a 0.5 mm/min crosshead speed. Wilcoxon's rank-sum test and Weibull statistics were used for statistical analysis (α = 0.05).
  
  
  RESULTS
  L structures recorded significantly higher values of load to fracture than the Z group both before and after veneering. Within each ceramic group, no differences were found between unveneered and veneered frameworks.
  
  
  CONCLUSIONS
  Although further studies are necessary to corroborate these findings, both zirconia systems could be recommended for restoring posterior teeth on the basis of the fracture load values recorded in this experiment (>1000 N). The veneering procedure did not affect the overall load to fracture in any group.
authors.affiliation: Department of Buccofacial Prostheses, Faculty of Odontology, Complutense University of Madrid (UCM), Madrid, Spain.
authors.forename: Verónica
authors.initials: V
authors.lastname: Rodríguez
authors.affiliation: Department of Buccofacial Prostheses, Faculty of Odontology, Complutense University of Madrid (UCM), Madrid, Spain.
authors.forename: Raquel
authors.initials: R
authors.lastname: Castillo-Oyagüe
authors.affiliation: Department of Buccofacial Prostheses, Faculty of Odontology, Complutense University of Madrid (UCM), Madrid, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: López-Suárez
authors.affiliation: Department of Buccofacial Prostheses, Faculty of Odontology, Complutense University of Madrid (UCM), Madrid, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Gonzalo
authors.affiliation: Department of Buccofacial Prostheses, Faculty of Odontology, Complutense University of Madrid (UCM), Madrid, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Peláez
authors.affiliation: Department of Buccofacial Prostheses, Faculty of Odontology, Complutense University of Madrid (UCM), Madrid, Spain. mjsuarez@odon.ucm.es.
authors.forename: María-Jesús
authors.initials: MJ
authors.lastname: Suárez-García
mesh_terms: D017076:Computer-Aided Design; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003801:Dental Veneers; D006801:Humans; D008422:Materials Testing; D011897:Random Allocation; D015040:Zirconium
chemical_list: D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide
keywords: CAD/CAM; FDPs; dental framework, ceramic veneering; fracture load; zirconia ceramic