title: Effect of the infrastructure material on the failure behavior of prosthetic crowns.
abstract: OBJECTIVE
  To evaluate the effect of infrastructure (IS) material on the fracture behavior of prosthetic crowns.
  
  
  METHODS
  Restorations were fabricated using a metal die simulating a prepared tooth. Four groups were evaluated: YZ-C, Y-TZP (In-Ceram YZ, Vita) IS produced by CAD-CAM; IZ-C, In-Ceram Zirconia (Vita) IS produced by CAD-CAM; IZ-S, In-Ceram Zirconia (Vita) IS produced by slip-cast; MC, metal IS (control). The IS were veneered with porcelain and resin cemented to fiber-reinforced composite dies. Specimens were loaded in compression to failure using a universal testing machine. The 30° angle load was applied by a spherical piston, in 37°C distilled water. Fractography was performed using stereomicroscope and SEM. Data were statistically analyzed with Anova and Student-Newman-Keuls tests (α=0.05).
  
  
  RESULTS
  Significant differences were found between groups (p=0.022). MC showed the highest mean failure load, statistically similar to YZ-C. There was no statistical difference between YZ-C, IZ-C and IZ-S. MC and YZ-C showed no catastrophic failure. IZ-C and IZ-S showed chipping and catastrophic failures. The fracture behavior is similar to reported clinical failures.
  
  
  CONCLUSIONS
  Considering the ceramic systems evaluated, YZ-C and MC crowns present greater fracture load and a more favorable failure mode than In-Ceram Zirconia crowns, regardless of the fabrication type (CAD-CAM or slip-cast).
authors.affiliation: Post-graduate Program in Dentistry, Dental School, University of Passo Fundo, Passo Fundo, RS, Brazil.
authors.forename: Queli Nunes
authors.initials: QN
authors.lastname: Sonza
authors.affiliation: Post-graduate Program in Dentistry, Dental School, University of Passo Fundo, Passo Fundo, RS, Brazil.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Della Bona
authors.affiliation: Post-graduate Program in Dentistry, Dental School, University of Passo Fundo, Passo Fundo, RS, Brazil. Electronic address: marcia_borb@hotmail.com.
authors.forename: Márcia
authors.initials: M
authors.lastname: Borba
mesh_terms: D003442:Crowns; D003764:Dental Materials; D019232:Dental Restoration Failure
chemical_list: D003764:Dental Materials
keywords: Ceramics; Dental materials; Dental restoration failure.; Stress, Mechanical