White Aluminum Oxide (White Alumina, α-Al₂O₃) is a high-purity, synthetic abrasive used extensively in dentistry for its exceptional combination of hardness, sharpness, and biocompatibility. It is the material of choice for finishing and polishing high-strength dental ceramics and metal alloys without causing chromatic contamination.
| Typical Chemical composition | |
| AL2O3 | 99.3%min |
| SiO2 | 0.06% |
| Na2O | 0.3%max |
| Fe2O3 | 0.05%max |
| CaO | 0.04%max |
| MgO | 0.01%max |
| K2O | 0.02#max |
| Typical physical properties | |
| Hardness: | Mohs:9.0 |
| Maximum service temperature: | 1900 ℃ |
| Melting Point: | 2250 ℃ |
| Specific Gravity: | 3.95g/cm3 |
| Volume density | 3.6g/cm3 |
| Bulk density(LPD): | 1.75-1.95 g/cm3 |
| Color: | White |
| Particle shape: | Angular |
| Available size: | |
| FEPA | F230 F240 F280 F320 F360 F400 F500 F600 F800 F1000 F1200 F1500 |
| JIS | 240# 280# 320# 360# 400# 500# 600# 700# 800# 1000# 1200# 1500# 2000# 2500# 3000# 4000# 6000# 8000# 10000# |
Key Advantages:
High Hardness (Mohs 9): Effective on all dental materials, including zirconia, lithium disilicate, and cobalt-chromium alloys.
Sharp, Friable Grains: The grains fracture to maintain sharp cutting edges, providing consistent, fast, and cool cutting action.
High Purity & White Color: Prevents discoloration of light-colored restorations (e.g., ceramics, composites), a critical aesthetic requirement.
Chemical Inertness & Biocompatibility: Safe for intraoral use and stable in various polishing environments.
Technical Specifications & Selection Criteria
Grit Size & Grading (FEPA Standard):
Coarse (P80 – P120): For rapid removal and major contour changes.
Medium (P150 – P320): For finishing, removing coarse scratches, and establishing basic shape.
Fine (P400 – P800): For pre-polishing, creating a smooth, satin finish.
Extra/Super Fine (P1200+ & Micron Grades): For final high-gloss polishing.
Particle Shape:
Bonded & Air-Abrasion: Particles are angular and blocky to maximize cutting efficiency.
Polishing Pastes: Often use spheroidized or rounded particles in the finest grades to burnish the surface without creating new scratches, transitioning from cutting to a smoothing action.
Dispersion & Carrier: High-quality pastes ensure uniform particle suspension to prevent settling and deliver consistent performance. The carrier must be non-toxic and easy to clean.