title: Mechanical properties of In-Ceram Alumina and In-Ceram Zirconia.
abstract: OBJECTIVE
  This study compared the mechanical properties of In-Ceram Zirconia and In-Ceram Alumina.
  
  
  METHODS
  Ninety-four disks and six bars were prepared with the slip-casting technique. The disks were used to assess biaxial flexural strength (piston on three ball), Weibull modulus, hardness, and fracture toughness with two methods: indentation fracture and indentation strength. The bars were used to measure elastic moduli (Young's modulus and Poisson's ratio). X-ray diffraction analysis of the specimens was carried out upon every step of the specimen preparation and of the fractured surfaces.
  
  
  RESULTS
  Mean biaxial flexure strengths of In-Ceram Alumina and In-Ceram Zirconia were 600 MPa (SD 60) and 620 MPa (SD 61), respectively. Mean fracture toughness measured according to indentation strength was 3.2 MPa.m1/2 (SD 0.34) for in-Ceram Alumina and 4.0 MPa.m1/2 (SD 0.43) for In-Ceram Zirconia. Mean fracture toughnesses of In-Ceram Alumina and In-Ceram Zirconia measured according to indentation fracture were 2.7 MPa.m1/2 (SD 0.34) and 3.0 MPa.m1/2 (SD 0.48), respectively. X-ray diffraction analysis showed that little phase transformation from tetragonal to monoclinic occurred when the specimens were fractured, supporting the existence of a modest difference of fracture toughness between the two ceramics.
  
  
  CONCLUSIONS
  No statistically significant difference was found in strength. In-Ceram Zirconia was tougher (P < .01) than In-Ceram Alumina when tested according to indentation strength. However, no significant difference was found in the fracture toughness when tested with the indentation fracture technique.
authors.affiliation: Biomaterials Science Research Unit, Faculty of Dentistry, University of Sydney, Suite G11, National Innovation Centre, Australian Technology Park, Eveleigh, New South Wales 1430, Australia. mgua4785@mail.usyd.edu.au
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Guazzato
authors.forename: Mohammad
authors.initials: M
authors.lastname: Albakry
authors.forename: Michael Vincent
authors.initials: MV
authors.lastname: Swain
authors.forename: Jim
authors.initials: J
authors.lastname: Ironside
mesh_terms: D000537:Aluminum Oxide; D003776:Dental Porcelain / Q000737:chemistry*; D004055:Differential Thermal Analysis; D004548:Elasticity; D006244:Hardness; D008422:Materials Testing; D019563:Mechanics; D016876:Metal Ceramic Alloys / Q000737:chemistry; D018583:Pliability; D014961:X-Ray Diffraction; D015040:Zirconium
chemical_list: D016876:Metal Ceramic Alloys; D003776:Dental Porcelain; D015040:Zirconium; D000537:Aluminum Oxide; C028541:zirconium oxide