title: Evaluation of hardness and fracture toughness, coupled with microstructural analysis, of zirconia ceramics stored in environments with different pH values.
abstract: The aim of this study was to evaluate the effects of pH changes in the oral cavity on the mechanical properties of zirconia and feldspathic ceramics. Bilayered zirconia-feldspathic samples were prepared from three different commercial brands of Y-TZP blocks: Zirkonzahn, Cercon, and Everest. Samples were stored in artificial saliva with different pH values (3.5, 7.0, and 10.0) for 10 days at 37°C. Flexural strength, Vickers hardness, and fracture toughness were calculated after samples were subjected to biaxial flexure test. Microstructural analysis of the materials was also performed.Data were analyzed by one-way analysis of variance (ANOVA), and multiple comparisons were performed using Tukey's test (α=0.05). Acidic and alkaline environments adversely affected the mechanical properties of zirconia, resulting in material degradation, loss of stabilizer content, and increase in tetragonal-monoclinic phase transformation. Commercial dental zirconia blocks have varied mechanical properties, but they are generally susceptible to degradation when exposed to corrosive environments.
authors.affiliation: Faculty of Dentistry, Department of Prosthodontics, Istanbul University, 34093 Fatih, Istanbul, Turkey. volkanturp@yahoo.com
authors.forename: Volkan
authors.initials: V
authors.lastname: Turp
authors.forename: Betul
authors.initials: B
authors.lastname: Tuncelli
authors.forename: Deniz
authors.initials: D
authors.lastname: Sen
authors.forename: Gultekin
authors.initials: G
authors.lastname: Goller
mesh_terms: D003080:Cold Temperature; D003343:Corrosion; D003799:Dental Stress Analysis; D006244:Hardness; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D018583:Pliability; D058105:Polymerization; D012464:Saliva, Artificial / Q000737:chemistry; D014961:X-Ray Diffraction; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D012464:Saliva, Artificial; C499362:yttria stabilized tetragonal zirconia; D015019:Yttrium; D015040:Zirconium