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Microstructural and crystallographic surface changes after grinding zirconia-based dental ceramics
1Section of Restorative and Prosthetic Dentistry, College of Dentistry, Ohio State University, 305 W. 12th Avenue, P.O. Box 182357 Columbus, Ohio 43218-2357, USA. denry.l@osu.edu
Journal of Biomedical Materials Research. Part B, Applied Biomaterials
|September 27, 2005
Summary
Grinding yttria-stabilized zirconia dental ceramics (3Y-TZP) introduces rhombohedral phases and lattice strain. Annealing removes these changes, but grinding causes surface damage impacting long-term performance.
Area of Science:
- Materials Science
- Biomaterials Engineering
- Dental Ceramics
Background:
- 3Y-TZP (3 mol% yttria-stabilized tetragonal zirconia) is a widely used dental ceramic.
- Surface treatments like grinding can alter the material's properties.
- Understanding phase transformations is crucial for predicting material behavior.
Purpose of the Study:
- To investigate microstructural and crystallographic phase changes in 3Y-TZP after grinding.
- To evaluate the effect of post-grinding treatments (polishing, annealing) on these changes.
Main Methods:
- Specimens were sintered, then divided into four groups: control, diamond-ground, ground and polished, ground and annealed.
- X-ray diffraction (XRD) was used for crystallographic phase analysis.
- Scanning Electron Microscopy (SEM) was employed for microstructural investigation.
Main Results:
- As-sintered and annealed 3Y-TZP showed only tetragonal zirconia.
- Grinding (with or without polishing) induced rhombohedral zirconia and strained tetragonal zirconia.
- Annealing at 1000°C for 1 hour eliminated residual strain and rhombohedral phase.
- Grinding and polishing resulted in surface damage and grain pullout up to 20 micrometers.
Conclusions:
- Grinding 3Y-TZP creates detrimental phases and surface damage.
- Annealing can recover the tetragonal phase but not repair surface damage.
- Surface integrity is critical for the fatigue resistance of 3Y-TZP dental ceramics.