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Microstructural and crystallographic surface changes after grinding zirconia-based dental ceramics.

Denry IL, Holloway JA

Section of Restorative and Prosthetic Dentistry, College of Dentistry, Ohio State University, 305 W. 12th Avenue, P.O. Box 182357 Columbus, Ohio 43218-2357.

The purpose of this study was to evaluate microstructural and crystallographic phase changes after grinding 3Y-TZP dental ceramics. Ceramic blanks were sintered according to manufacturer's recommendations and divided into four groups: (A) as-sintered control, (B) diamond-ground manually under water, (C) ground and polished, and (D) ground and annealed at 1000 degrees C for 1 h. Bulk specimens were analyzed by X-ray diffraction to characterize the crystalline phases. The microstructure was investigated by SEM. XRD analyses showed that the control group and the group that was ground and annealed contained only tetragonal zirconia. However, after grinding or after grinding followed by polishing, rhombohedral zirconia and strained tetragonal zirconia were present, without any detectable amount of monoclinic zirconia. Annealing led to the disappearance of both residual lattice strain and the rhombohedral phase. The microstructure of the ground and polished specimens was characterized by significant residual surface damage associated with grain pullout to a depth of about 20 mum. This type of damage could have an impact on the long-term fatigue behavior of 3Y-TZP. (c) 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006.

Published 9 January 2006 in J Biomed Mater Res B Appl Biomater, 76(2): 440-8.
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