Classifications of Dental Burs - Understanding the ISO Code

Classifications of Dental Burs - Understanding the ISO Code


Dental burs are used to polish and cut the mouth’s hard tissues. These nifty little devices are typically attached to a handpiece. They are often made of diamond grit, tungsten carbide, or steel and come in a wide range of shapes and sizes to suit the different procedures carried out by dentists.


The typical bur consists of three different parts: the shank, which is the longest and is inserted into or attached to a handpiece; the rotating head, which is used to cut or polish the tissue; and the neck, which connects the shank and the head.


The numbering system for dental burs used by the ISO


In the ISO system, burs are coded with a 15-digit number. This makes it easy to precisely identify any specific bur. This ISO code consists of the following 5 sections, each of which uses a 3-digit code to describe the bur:


- The type of material the bur is made of

- The shank type and total length of the bur

- The shape of the head

- The size of the grit

- The maximum diameter of the head


Let’s briefly examine the various code sections:


1. The type of material


In the past, dental burs were often made of steel but more recently two new materials that have proven to be more durable and have better cutting qualities have come to the forefront :


- Diamond dental burs are used to cut tooth enamel, the hardest substance found in the hu-man body. The typical diamond bur features a shank made of steel and a head coated with ei-ther synthetic or natural diamond powder.

- Tungsten carbide dental burs are fast replacing steel burs. These are extremely efficient, much more rigid than steel, and remarkably durable.


2. The shank type and total length of the bur


- Contra-angle dental burs. These have a diameter of 2.35mm and they typically have a notch at the rear end. They are often also called CA (low-speed) burs or RA (Right-Angle) burs.

- Turbine dental burs. With these burs, the shank has a diameter of 1.6 mm and the end is ex-posed. They are sometimes also referred to as FG (Friction Grip) burs, high-speed burs, or high-rotation burs.

- Handpiece burs. Similar to their contra-angle counterparts, these also have a 2.35 mm shank diameter but the bur itself is much longer. These are often also known as HP burs.


3. The shape of the bur


The third 3-digit section of the 15-digit ISO code names burs depending on how similar they are to some well-known objects. There’s quite a bewildering variety of options here, including:


- Cylindrical burs are e.g. used in ceramic crown preparations to shape the chamfer.

- Ball burs are typically used to make grooves for prosthetics and to open cavities.

- Inverted cone burs are often also used to open cavities or make undercuts during dental sur-gery.

- Conical burs have flat or rounded tips. The former type is often used for chamfering.

- Wheel burs are typically used to make occlusal shapes, deep cuts, or mechanical retentions.


Note: There are many other different types.


4. The grit size


The fourth 3-digit section of the ISO code refers to the dental bur’s grit size. One will normally see a colored ring around the bur’s neck that indicates how coarse the grain is. This can vary from white (super fine) to black (super coarse). In between, there are four other colors (yellow, red, blue, green) indicating increasing degrees of coarseness.


5. The bur’s head diameter


The final 3-digit section of the ISO code for dental burs refers to the maximum diameter of their most active part, the head. Suffice to say, there are numerous different sizes.


This section provides the most concise classification of dental burs. The bigger sizes are typically used during dental surgery, while the smaller sizes are more suitable for work that requires a great deal of detail.



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