title: Fractographic principles applied to Y-TZP mechanical behavior analysis.
abstract: The purpose of this study was to evaluate the use of fractography principles to determine the fracture toughness of Y-TZP dental ceramic in which KIc was measured fractographically using controlled-flaw beam bending techniques and to correlate the flaw distribution with the mechanical properties. The Y-TZP blocks studied were: Zirconia Zirklein (ZZ); Zirconcad (ZCA); IPS e.max ZirCad (ZMAX); and In Ceram YZ (ZYZ). Samples were prepared (16mm×4mm×2mm) according to ISO 6872 specifications and subjected to three-point bending at a crosshead speed of 0.5mm/min. Weibull probability curves (95% confidence bounds) were calculated and a contour plot with the Weibull modulus (m) versus characteristic strength (σ0) was used to examine the differences among groups. The fractured surface of each specimen was inspected in a scanning electron microscope (SEM) for qualitative and quantitative fractographic analysis. The critical defect size (c) and fracture toughness (KIc) were estimated. The fractured surfaces of the samples from all groups showed similar fractographic characteristics, except ZCA showed pores and defects. Fracture toughness and the flexural strength values were not different among the groups except for ZCA. The characteristic strength (p<0.05) of ZZ (η=920.4) was higher than the ZCA (η=651.1) and similar to the ZMAX (η=983.6) and ZYZ (η=1054.8). By means of quantitative and qualitative fractographic analysis, this study showed fracture toughness and strength that could be correlated to the observable microstructural features of the evaluated zirconia polycrystalline ceramics.
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
authors.forename: Carla Müller
authors.initials: CM
authors.lastname: Ramos
authors.affiliation: Department of Biomaterials and Oral Biology, Faculty of Dentistry, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Paulo Francisco
authors.initials: PF
authors.lastname: Cesar
authors.affiliation: Department of Prosthetic Dentistry, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
authors.forename: Estevam Augusto
authors.initials: EA
authors.lastname: Bonfante
authors.affiliation: Department of Prosthetic Dentistry, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
authors.forename: José Henrique
authors.initials: JH
authors.lastname: Rubo
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil.
authors.forename: Linda
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil. Electronic address: afborges@fob.usp.br.
authors.forename: Ana Flávia Sanches
authors.initials: AF
authors.lastname: Borges
mesh_terms: D008422:Materials Testing; D055595:Mechanical Phenomena; D013314:Stress, Mechanical; D013499:Surface Properties; D015019:Yttrium; D015040:Zirconium
chemical_list: C499362:yttria stabilized tetragonal zirconia; D015019:Yttrium; D015040:Zirconium
keywords: Ceramic; Zirconium