Contamination of dental zirconia before final firing: effects on mechanical properties.
Plate-like specimens were prepared, using a diamond saw, from Cercon -a pre-sintered yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) block. These specimens were treated with 10 kinds of dental materials which acted as contaminants, and then sintered at 1,350°C or 1,450°C. After the final firing, specimens were subjected to a three-point flexural test and Vickers hardness test. Their surfaces were also characterized by scanning electron microscopy and X-ray diffractometry. Phosphorus-containing contaminants reduced the three-point flexural strength and hardness of final sintered zirconia due to the formation of YPO4 and phase transformation from tetragonal to monoclinic zirconia. Gypsum also reduced both mechanical properties due to the formation of CaZrO3 and phase transformation from tetragonal to cubic zirconia. Other contaminants showed no adverse effects on the mechanical properties of final sintered zirconia.
Department of Dental Materials Science, School of Dentistry, Aichi Gakuin University.
Seiji
S
Ban
Yuji
Y
Okuda
Makoto
M
Noda
Jiro
J
Tsuruki
Tatsushi
T
Kawai
Hiroshi
H
Kono
D003764:Dental Materials; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D014961:X-Ray Diffraction; D015040:Zirconium
D003764:Dental Materials; D015040:Zirconium; C028541:zirconium oxide