Air rotor high-speed bur used during dental procedures, usually to remove decay and shape tooth structure prior to the insertion of a filling or crown. A dental bur may also be used in the cleaning and shaping of root canals during endodontic treatment, or to remove old or temporary fillings or crowns prior to the insertion of new or permanent restorations. Air rotor burs can rotate at up to 400,000 rpm. Dental bur come in a great variety of shapes designed for specific applications. They are often made of steel with a tungsten carbide coating, or of tungsten carbide entirely. The bur may also have a diamond coating. There are various shapes of burs that include round, inverted cone, straight fissure, tapered fissure, and pear-shaped burs.