Rotary instruments are dental cutting instruments driven by handpieces, to which a dental bur (rotary drill) made of steel, tungsten, carbide or diamond is attached.
The three parts to a burr are the head, the neck, and the shank.
The shank is usually the longest part of the bur and is inserted into the handpiece. The neck is connected to the head, which contains the bur.
Since their primitive origins several millennia ago, burs have come a long way from crude beginnings as primitive cutting devices to modern, efficient tools made from high-tech materials — primarily steel, carbide, diamond and ceramics.
18th and early 19th centuries — Hand burs
19th century — evolution of the dental drill
1870 — Morison patented the treadle engine powered by foot pedals
1893 — Doriot’s electric motor to directly power the handpiece.
1957 — S. S. White company introduced the high-speed handpiece — the Borden Airotor.
Today’s high-speed handpieces operate at speeds (faster than a jet engine) of more than 300,000 rpm5.
Types of Burs:
Carbide, steel, diamond, ceramic and polymer burs.
Tungsten Carbide burs:
Carbide burs are commonly used to remove material and tooth structure. They leave a smooth surface and can be sharpened and reused. They come in various shapes and sizes and have a coating that increases tool life.
Tungsten carbide contains equal parts carbon and tungsten, is stiffer and much denser than steel or titanium.
Most of the dental burs are tungsten carbide and are preferred for their cutting efficacy with air turbine and electric handpieces.
Steel burs are similar to carbide burs, but they are softer and more flexible.
They are generally preferred for cutting through porcelain fixtures like Zirconia and lithium disilicate materials.
Diamond burs have a variety of grit sizes.
Coarse and super-coarse — for tooth reduction.
Fine and super-fine — for polishing and smoothing.
Diamond burs come in two types: single-use and multi-use.
Single-use diamond burs — individually packaged pre-sterilized diamond.
Multiuse diamonds — to be re-used for many procedures, more economical, many shapes and grits available.
Diamond abrasives consist of three parts — a metal blank, powdered diamond abrasive and a metallic bonding agent which holds the diamond abrasive onto the metal blank.
Polymer and ceramic burs preserve healthy dentin, effectively remove caries and are used for the surgical shaping of bone.
Burs come in several shapes, such as round, straight, conical, inverted cone, straight fissure, tapered fissure, and pear-shaped.
Round burs — to remove of large amounts of tooth decay
Flat-end burs — to remove tooth structure
Smaller, pointed burs — for precise cutting
Burs with cross-cuts — reduce vibrations
Dentals Inc. have a wide range of burs with different shapes of shanks and handpieces.