Types of Carbide Bur Shapes

The cutting end of the bur is named by its shape. There are a variety of shapes available, each suited to a particular task. Some of the most popular are round, pear, inverted cone, straight fissure, and tapered fissure. Different flute angles also create different cutting characteristics and make a particular bur more appropriate for a certain task.

Operative, or cavity preparation burs, have deep and wide flutes which allow for more aggressive enamel cutting with higher speed and efficiency. These operative burs are usually either straight-bladed (plain) or crosscut.

Straight-bladed burs cut smoothly but more slowly, especially with harder materials. Crosscut burs have additional cuts across the blades (these are the crosscuts) to create increased cutting efficiency. While the benefit of these extra blades has been minimized in recent years with the advent of high-speed handpieces (which cut more efficiently), crosscut burs can generally cut more quickly because debris does not build up on the bur.

Trimming and finishing burs have more blades than operative burs, and the blades are closer together and shallower, which makes these burs ideal for the fine finishing and polishing of dental materials.

Each type of bur shape has a number designation, with the head of the bur generally increasing in size as the number gets larger within a particular shape series. For example, round burs come in sizes from 1⁄4 to 8, with 8 having a much larger head than 1⁄4.