The high-speed handpiece is an essential piece of equipment for dental extractions and other procedures. It is used to remove bone and section multi-rooted teeth so individual crown-root segments may be extracted as if they were single-rooted teeth.
The high-speed handpiece is driven by air and relies on revolutions per minute (RPM) to accomplish its job. It typically runs at 200,000 to 400,000 RPM. Since the air-driven handpiece relies on RPMs and not torque, it is most efficient when used with a light touch and with the foot pedal (also called rheostat) pushed to the floor. Pressing too hard with the handpiece will result in the binding of the bur and that unpleasant smell of burnt hard tissue. Eye and face protection should always be used when using burs.
The burs used in a high-speed handpiece are called FG burs, which stands for "friction grip." FG burs are secured with either a push-button mechanism or a wrench. Push-button handpieces predominate because they are more convenient.
Handpieces secured with a wrench require more time to switch from bur to bur but tend to be more durable than push-button handpieces. After placement of a bur in the push-button handpiece, the bur is tugged on to ensure it is well seated in the handpiece. Standard-length FG burs are 19 mm long, whereas surgical-length FG burs are 25 mm long.
Types of handpieces
1) High-speed handpieces. My above description is of the air-driven high-speed handpiece, but there is also an option for a high-speed handpiece made specifically for an electric micromotor. Electric handpieces have more torque than air-driven units and cut through bone with the most efficiency. Since they are powerful and do not bind, adequate water cooling and avoiding soft tissue areas are important.
The electric handpiece tends to be heavier than an air-driven handpiece (Figure 1). Both are held with a "modified pen grasp," which provides the best control over the tiny burs placed in the head of the handpiece.
2) Low-speed handpieces. In contrast to a high-speed handpiece that only accepts FG burs, a low-speed handpiece accepts the following: 1) a prophy angle for polishing, 2) handpiece (HP) burs (44.5 mm long straight burs often used for rabbit and rodent dentistry), or 3) an attachment that allows for latch attachment (LA) burs.
The low-speed handpiece relies on torque rather than RPM. The LA burs and HP burs on a low-speed handpiece do not cut through teeth with nearly the efficiency of the FG burs on a high-speed air-driven or electric handpiece.
Types of burs
General practitioners often ask, "What burs do I need?" A large variety of burs are helpful in veterinary dentistry, and every veterinary dentist has their favorites. In this column, I will focus on what I perceive to be the essential list of burs for every general practice performing extractions in dogs and cats (Figure 2).
Round burs
These are helpful to remove bone and expose a firmly rooted tooth root. Round burs come in sizes ranging from small to large: ¼, ½, 1, 2, 4, 6, 8. A general rule of burs: the larger the working end of a bur, the more damage you will cause if the bur's swirling vortex pulls in and wraps up adjacent soft tissue. Therefore, I try to use the smallest size that gets the job done.
When I am making a large window lateral to the root of a dog's canine tooth, I may use a #4 round bur. When I am making that window lateral to the root of a cat's canine tooth, I will use a #2 round bur. The ¼ round bur is my "go-to" bur in cases where any wrong move can result in unwanted damage to adjacent soft or hard tissue.
For example, the ¼ round bur is wonderful for removing broken root tips by creating a small moat around the root and a small lateral window to allow for the placement of a small dental elevator on the palatal or lingual side of the root to pry the root tip from its socket gently. Be careful when using the ¼ round bur, as the working end of the bur may separate from the shaft of the bur, especially if the operator presses too firmly. Certain manufacturers of the ¼ round bur seem to do a better job of preventing this complication from happening.
Due to concerns about bur separation with the ¼ round bur, some practices use a ½ bur as their smallest round bur. Whichever one you decide to have for your practice, do not reuse them, and get the surgical length instead of the standard length.
Crosscut fissure bur
I use the #701 crosscut fissure bur to section multi-rooted feline teeth. Some dentists prefer a daintier #699 bur for sectioning cat teeth, but ensure you wear eye protection since the tips of the working end can break off and become a projectile. I use a surgical-length #702 bur to section multi-rooted teeth in dogs.
The "L" next to a designation of #701 L or #702 L refers not to a longer overall bur length but rather a longer cutting portion of the working end.
Diamond bur
The #23 diamond bur is different than the other burs described here. Until now, all burs discussed were carbide burs, which come with aggressive-cutting flutes.
Carbide burs melt away bone with ease and cut through tooth structure more efficiently than diamond burs. I use diamond burs for a variety of reasons, but most commonly, they are used to smooth the rough edges of an extraction site before closure. All burs can accidentally wrap up adjacent soft tissues, but diamond burs are less likely to do so compared to carbide burs.
When removing bone to expose roots, think of yourself as an archaeologist at a dig, looking to unearth a precious relic that must not be damaged. Removing the thin layer of bone covering the lateral surface of the roots will increase your odds of removing the root, but drilling deep into the root structure will increase the chances of the root breaking when elevating with the dental elevator. Practice makes perfect.
Should burs be discarded after a single use? Some are specifically designated as "single-use." Many handpiece manufacturers recommend discarding all burs after a single use to extend the life of your turbines. We reuse certain carbide burs and diamond burs, sterilizing them between uses. We discard our ¼ round burs after a single use.
John R. Lewis, VMD, DAVDC, Fellow, AVDC OMFS, practices at Veterinary Dentistry Specialists and teaches at Silo Academy Education Center, both located in Chadds Ford, Pa.
