The Ultimate Guide to Dental Burs
What are dental burs?
Dental burs attach to a handpiece and are used for cutting and polishing hard tissues of the mouth. There’s a huge range available depending on the type of procedure that’s being undertaken. Typically they are made of steel, tungsten carbide or diamond grit.
Burs have three parts: the head, the neck and the shank. The head contains blades which rotate to cut the tissue. The shank is the longest part and is inserted into the handpiece. The neck connects the two parts.
The angle and positioning of the blades and the shape of the head determines the bur’s use.
Diamond burs (ISO 806) are widely used by dentists around the world, most often with high speed handpieces. Diamond is able to grind away hard tissues such as enamel and bone, leaving a rough surface. They are formed by bonding small particles of diamond onto a substrate. Most commonly they come with a friction grip (FG) shank. They’re designed to reduce tooth structures and are commonly used for crown and veneer related procedures. High quality, they offer tremendous accuracy, allowing a fast and smooth cut. However they tend to have a shorter lifespan than other types of burs; repeated sterilization reduces their cutting effectiveness.
Coltene's Diatech gold diamond burs offer a high level of performance and durability. Only natural diamonds are used on all Diatech burs, for superior cutting efficiency and long instrument life.
Tungsten Carbide Burs
Tungsten Carbide burs (ISO 500) are also known for their excellent precision. Tungsten carbide burs are three times harder than steel and this alloy helps the dentist to smooth down tooth structures to an incredible finish. They are available with FG and RA shanks. They’re often used when trimming and finishing composite restorations. They’re higher priced than steel burs, but they compensate for this with a longer working life. They are known for their minimal vibration and ‘chatter’ compared to other types of dental burs, and tend to build up little debris in use.
Often a tungsten carbide bur actually only has carbide in the tip; the material is brittle compared to steel, so often the shank will still be made of steel.
Steel burs are known as much for their flexibility as they are their edge retention. They’re the great value, go-to everyday bur for removing dentin and cavity preparation. They are most commonly available with a latch type RA shank, and possess a high resistance to chipping and breaking away. However they tend to blunt faster than tungsten carbide burs, and can corrode.
The Difference between HP, RA and FG Dental Burs
HP or “handpiece” burs are the larger, long straight shank types with a shank diameter of 2.35mm. The length is defined by ISO numbers starting with 1XX. This particular type of bur is used on slow speed handpieces and are even used in surgery procedures as well as the reduction of the smaller cheek teeth.
FG or “friction grip” burs are used by dentists when working with high speed handpieces. They possess a smooth shaft and the length of the handle is defined by ISO numbers starting with 3XX. Typically they are around 20mm in length and 1.6mm in diameter.
RA or “right angle” burs latch on to low speed contra-angle handpieces with a notch at the end of the handle. Again they have a shaft diameter of 2.35mm and the length is defined by ISO codes starting with 2XX. They’re available with the same shapes as FG shanks.
Another way to classify burs is through their shape. Informally these might be known as “cone”, “round”, “spear” but the ISO system clearly defines each shape with a code.
In general, round and pear burs are used for cavity preparation and undercuts, cross-cut burs are used for crown work and sectioning multi-rooted teeth, and finishing burs are used for finishing restorations.
The colour band around the neck of a bur indicates its grit size, or “grain size”. Coarser grits are used when more material needs to be removed, for example when cleaning caries. Finer grits tends to be used for polishing and finishing work.
A final characteristic of a bur is the diameter of the head. The smallest sizes are used for more detailed work, whereas larger sizes are more common in surgical procedures.
ISO numbering system
The ISO system labels burs with a 15 digit code to enable precise identification. The code number is broken down into six sections: Type of bur / Type of shank / Bur length / Head shape / Grit size / Maximum head diameter
Dental burs from Kent Express
Kent Express offers a wide range of burs from all leading manufacturers, and encourage you to take advantage of our easy online ordering service. Our dedicated, experienced account managers are on hand to offer free advice and answer any questions you may have on 0800 028 1181. Lines are open between 8.30am and 5.30pm and we would love to hear from you today.