Biaxial Flexure Strength and Low Temperature Degradation of Ce-TZP/Al2O3 Nanocomposite and Y-TZP as Dental Restoratives

The purpose of the present study was to evaluate the mechanical durability of a zirconia/alumina nanocomposite stabilized with cerium oxide (Ce-TZP/Al2O3 nanocomposite) in comparison to yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) and discuss its application on ceramic dental restorations. The disk-shaped specimens of both materials were stored in physiological saline solution at 80 degrees C for 30 days, in 4% acetic acid at 80 degrees C for 30 days, and in an autoclave at 121 degrees C for 10 days. Before and after storage, specimens were subjected to the biaxial flexure test and to the determination of the monoclinic zirconia content. After autoclaving, Y-TZP showed remarkable increasing of the content of monoclinic zirconia: 0.3 vol% before and 49.9 vol% after, and slight decreasing of biaxial flexure strength: 1046 MPa before and 892 MPa after; whereas Ce-TZP/Al2O3 nanocomposite showed no significant difference in the monoclinic content (4.8-5.5 vol%) and the biaxial flexure strength (1371-1422 MPa) after storage in any conditions. It is concluded that, compared to Y-TZP, the Ce-TZP/Al2O3 nanocomposite has a high biaxial flexure strength along with a satisfactory durability in terms of low-temperature aging degradation in above conditions. This study indicates that the Ce-TZP/Al2O3 nanocomposite demonstrates excellent mechanical durability for dental restorations such as all-ceramic bridges. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 87B: 492-498, 2008