Dental Highspeed Handpieces: The Causes Of Chuck Failure & How You Can Prevent It

The Chucks in Dental Highspeed Handpieces Fail Most Often Due to a Process Known as Aspiration:

  • That is, when you take your foot off the foot pedal, the Physics of the Handpiece are momentarily reversed and a Vacuum is created. As a result, microscopic debris is sucked into the Chuck.

When the Handpiece is Sterilized the debris hardens. This process is repeated over and over again and the debris eventually becomes a growing mass.

As the mass grows, it begins to fill the chuck cavity and eventually reaches a depth that keeps the bur from fully seating. At that time, the chuck will no longer be able to hold the bur and it will fall out. Chuck replacement will then be required.

This type of failure is preventable. The key is to catch and remove the debris before it reaches the hardened stage. The way to accomplish this is with a good grade of chuck cleaner. Star Dental has a product called “Junk Out.” It comes in a kit that includes a cleaning brush, which can be inserted into the chuck to insure all particulates are removed. It sells for around $25.00 and will last the average practice a year or more. To keep warranties in force, Chuck Cleaning is a required procedure for all Highspeeds; including the “Maintenance Free” and “Life Time Lube” Handpieces. Try to set up a cleaning schedule of once a week and stay with it. Another problem we often see is the bur getting stuck inside the Highspeed Handpiece. Never pull the bur out with pliers! The force created when using pliers will damage the chuck beyond repair. The bur generally gets stuck for one of two reasons: The aspiration process described above or by using a bur with a shank that is too short. To determine if the shank is too short, use this as a general rule of thumb: if the tapered portion of the bur goes inside the chuck opening, it’s too small. Don’t use it! If the chuck is allowed to close on this taper, the normal opening range of the chuck will no longer be sufficient to release the bur.

The tolerances are measured in one-ten-thousandth of an inch, so it doesn’t take much of a taper to lock up the bur permanently If your current Repair Facility hasn’t explained this to you, maybe it’s time to change Handpiece Repair companies.

At, we not only deliver expert repairs, we also strive to help prevent problems from occurring in the first place. We believe it makes for a better relationship for all of us.Today’s Chuck Assemblies are designed to last for years, and will – if properly maintained. Visit us at