title: Influence of grain size and veneer firing process on the flexural strength of zirconia ceramics.
abstract: The aim of the present investigation was to study the influence of grain size on the strength of yttria-stabilized zirconia upon exposure to an additional heat treatment, mimicking the veneering process. The green bodies of zirconia discs prepared by cold isostatic pressing were sintered at 1,425, 1,500, or 1,575°C to customize the grain size. The disc-shaped specimens were highly polished and then processed with or without additional heat treatments (five times at 850-930°C). Ten specimens from each treatment group were subjected to a biaxial flexural strength test according to the ISO 6872 standard. The grain size of the specimens was analyzed by the mean linear intercept technique using scanning electron microscopy. It was demonstrated that the mechanical strength of zirconia ceramics was not reduced by the veneer firing processes when polished specimens were used, but the strength was found to decrease with increasing grain size. The raw materials and the sintering process used should be selected appropriately to avoid grain coarsening because it was found that the strength was influenced by large grains.
authors.affiliation: Laboratory for Redox Regulation, Tohoku University Graduate School of Dentistry, Sendai, Japan. keisuke@m.tohoku.ac.jp
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nakamura
authors.forename: Erik
authors.initials: E
authors.lastname: Adolfsson
authors.forename: Percy
authors.initials: P
authors.lastname: Milleding
authors.forename: Taro
authors.initials: T
authors.lastname: Kanno
authors.forename: Ulf
authors.initials: U
authors.lastname: Örtengren
mesh_terms: D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D003801:Dental Veneers; D006358:Hot Temperature; D006801:Humans; D008422:Materials Testing; D018583:Pliability; D013314:Stress, Mechanical; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D015019:Yttrium; D015040:Zirconium