Dentists use dental abrasives often. Dentures, removable partials, crowns, bridges, and direct dental restoration materials are among the dental appliances finished and polished in this specialty. Hard minerals or synthetic stones are typically used as abrasives, even if some are chemically identical to naturally occurring minerals. Still, because they did not occur naturally, they cannot be called minerals.
Corundum, another naturally occurring mineral, and diamond are both manufactured industrially. Calcium carbonate, for instance, is used as a dental abrasive, such as a “polishing agent” in toothpaste.
Factors Affecting Abrasion
The clinician will be able to make appropriate clinical decisions by understanding the properties of abrasives and the factors controlling the abrasion rate. As abrasion occurs, it is caused by the size, irregularity, and hardness of the particles and their number, pressure, and speed. To control abrasion appropriately, clinicians must be aware of these factors.
Particle Size, Irregularity, and Hardness
An abrasive particle’s size, irregularity, and hardness determine how deeply it scratches the material’s surface and, therefore, how much is removed. Pumice can be found in various coarsenesses, and it can have a significant effect on cementum and amalgam. Compared to hard amalgam, coarse pumice will remove more surface area from the softer cementum. By using a much smaller and more regular particle of pumice flour as opposed to coarse pumice, the cementum and amalgam will be polished. Dental materials most often use diamonds for abrasive purposes. As you can see, diamond abrasives can remove large amounts of restorative material of tooth structure, finishing and polishing restorations. Also, the rate of the abrasion will depend on the material, the pressure, and the rotation speed.
In dentistry, various natural and synthetic (manufactured) materials can be utilized. The following materials are categorized by how abrasive they are, from most to least.
In mohs’ hardness scale, a diamond rates 10 out of 10. It makes it suitable for abrading any substance. Due to their cost and nondisposability, rotary diamonds are usually bonded to rotating disks or shanks in varying degrees of coarseness. Sterilized, they can be reused several times before wearing out. Diamond paste is used to polish composite and porcelain restorations. Crown and bridge preparations are cut with them, and composite restorations are polished with them.
2. Carbide Finishing Burs
With designs ranging from 7-30 cutting flutes, tungsten carbide finishing burs are available in several shapes. A bur with more flutes will have a finer finish. An eight-flute bur will cut very aggressively. On the Mohs’ scale, these burs rank between 8 and 9. Usually, they are used to finish composite restorations.
3. Silica Carbide
The material silicon carbide is an abrasive material that has a Mohs’ hardness of 9 to 10. It is mostly finishing procedures that use silicon carbide–coated disks and rotary elements.
4. Aluminum Oxide
The powdered form of aluminum oxide is usually white or tan. Sandblasting and air abrasion are used to prepare restorations for cementation. Rotating devices are bonded and coated with abrasion. Burlew wheels are made of rubber impregnated with aluminum oxide. Abrasives of this type are available in several grits and have largely replaced emery. It smooths enamel, metals, and ceramics.