the head of the handpiece. The contra-angle allows for
easy access to treatment sites. Straight designed
high-speed handpieces are available, but the
contra-angle is the most commonly used in restorative
procedures. Before you use one, consult the
appropriate manufacturers instructions.
The high-speed handpieces are designed to use
smooth shank burs that are 1/2-inch in length. All
models work on the same basic principle: Burs are
inserted into a plastic or metal friction chuck and held
tight in the handpiece by either manual tightening or a
power lever lock. The bur is rotated when air is forced
through the airports into the head of the handpiece and
to the air turbine.
The high-speed handpiece uses a water system to
keep the handpiece cool. The water system also
produces a fine spray mist, which aids in flushing
debris from the treatment site. Constant preventive
maintenance is essential in caring for handpieces. If
they are not properly cleaned and lubricated,
abrasives, such as finely ground tooth, metal, and other
particles, will cause excessive wear and undue
vibration. The proper lubrication of handpieces is of
such importance that it cannot be overstressed. Read
and follow the manufacturers instructions to make
sure that you understand the lubrication, cleaning,
Figure 11-8.High-speed contra-angle handpiece.
and sterilization requirements. Perform the necessary
maintenance as recommended. It takes only a few
seconds to ruin a handpiece that has been improperly or
insufficiently lubricated, cleaned, or sterilized. Always
ensure your handpieces meet the required infection
control standards as outlined in BUMEDINST 6600.10,
Dental Infection Control Program.
LOW- OR SLOW-SPEED
This type of handpiece is used for removing caries,
refining a cavity preparation, and performing a
The low-speed handpiece consists of a motor or
power driven unit (fig. 11-9) and various attachments
(fig. 11-10). The speed of the motor ranges from 0 to
5,000, or 80,000 rpm depending on the model.
The head of the handpiece attachment contains a
chuck into which a dental bur or other rotary
instrument is fitted. Most heads contain a latch-type
chuck. Some heads contain a friction-grip chuck. On
the slow-speed motor is a speed control ring. By
turning this ring, you can control the speed with which
a bur rotates and its direction of rotation.
Many units and models have some method of
quickly connecting and disconnecting the motor and
Some models have a quick ring
disconnect, while others have a button to depress or an
indicator to press. As with the high-speed handpiece,
read and follow the manufacturers instructions for
operation, lubrication, cleaning, and sterilization
requirements for the slow-speed motor and
Figure 11-9.Slow-speed motor.