Using white aluminum oxide (white fused alumina) for dental polishing is a highly specialized and critical application. It is one of the most common and important abrasives in dentistry due to its exceptional properties.

Here’s a detailed breakdown of its use in this field:

Why White Aluminum Oxide is Ideal for Dental Polishing

The requirements for dental polishing are extreme: it must be effective, precise, non-toxic, and produce a supremely smooth, non-abrasive surface. White aluminum oxide meets these demands perfectly:

1. High Hardness (Mohs 9): Hard enough to effectively abrade dental materials, including composites, ceramics (porcelain), acrylics (dentures), and even enamel and amalgam, but controllable to avoid excessive removal.

2. Exceptional Purity (>99% Al₂O₃): This is its most critical advantage for medical use. The high purity ensures it is chemically inert and non-toxic. It will not react with oral tissues or the restoration materials, preventing irritation, discoloration, or corrosion.

3. Sharp, Angular Particles: The particles fracture to form sharp edges, allowing for efficient cutting and a fine finish. This allows manufacturers to precisely grade the particles by size for predictable polishing steps.

4. White Color: This is neutral and will not stain or discolor the typically light-colored dental restorations (unlike some brown or pink abrasives that might leave a tint).

Common Forms in Dentistry

White aluminum oxide is rarely used alone; it is incorporated into various delivery systems:

1. Prophy Paste (Prophylaxis Paste):

   • This is the most well-known form. It’s the gritty paste used during a routine dental cleaning.

   • The white aluminum oxide micro-powder is suspended in a water-soluble, flavored gel or paste (often containing fluoride, humectants, and flavoring).

   • It is applied with a rubber cup attached to a slow-speed handpiece to polish tooth enamel after a scaling (cleaning) to remove stain and create a smooth, plaque-resistant surface.

2. Polishing Slurries and Pastes for Lab and Clinic:

   • Finer grades are used as a slurry with water or a specialized lubricant for polishing ceramic crowns, bridges, and composite restorations in the dental lab and at the chairside.

   • They are often used with felt wheels, bristle brushes, or foam points on a rotary handpiece.

3. Microetchant (Air-Abrasion):

• A stream of fine white aluminum oxide powder is propelled by compressed air onto a surface.
• Pre-treatment: Microscopically roughening the inside of a crown or the surface of a tooth to create a better bond for cement.
• Cleaning: Removing surface contaminants from restorations.
• Minimal Cavity Preparation: In some conservative techniques.