This system delivers the drive air and coolant to
whichever handpiece is lifted from the dental unit. The
control system is made up of two parts: handpiece
controls and a foot control.
HANDPIECE CONTROLS.Most handpiece
controls are located on the bracket tray that can
accommodate three handpieces (fig. 11-6). The water
coolant flow and maximum drive pressure are
individually adjustable for each handpiece.
Most units use the following international
A blue dot identifies a water control.
A yellow dot identifies an air control.
A red dot identifies the ON or active position.
Every dental unit has a master ON-OFF toggle or
switch. It turns on the air and water to the control
system. When it is turned off, none of the items on the
unit will function. This switch should be OFF
whenever the unit is not in use to prevent flooding in
the event of a leak while the system is unattended. The
ON/OFF indicator provides a visual indication that the
system is pressurized when the master switch is ON.
HANDPIECE HOSES.The handpiece hose is
attached to a coupling that joins the handpiece to the
hose. Never over-tighten the coupling. Under- tightening
Figure 11-6.Handpiece controls.
can cause air and waterleaks. Many providers use a
quick disconnect that attaches to the coupling. By
gently pulling on the handpiece, the operator is able to
change handpieces very quickly. The quick
disconnect is also available with a 360° swivel that
allows the handpiece to be turned around without
tangling up the hoses. Perform a daily operational
check on the quick disconnect equipment. Inspect O
rings and replace them if found frayed or missing.
operated by the provider through the use of a foot
control (rheostat) device. A valve inside the foot
control regulates the handpiece speed and provides an
air signal that activates the air and water coolant flow.
The foot control is operated by light foot pressure
applied to any part of the disk. Some foot controls may
also be equipped with a wet/dry toggle switch and a
chip blower. The wet/dry toggle switch can shut off
the water coolant to the handpiece without moving the
hands from the treatment area. The chip blower sends a
jet of air through the handpiece when not in use to
remove any debris accumulated in the treatment site.
The other controls that could be on the bracket
table and assembly, depending on the make and model,
are as follows:
WATER COOLANT ON/OFF TOGGLE
Stops the flow of water coolant to all handpieces.
AIR COOLANT FLOW CONTROLAdjusts
the air coolant flow to all handpieces and can
completely shut off the air coolant.
DRIVE AIR PRESSURE CONTROLAdjusts
the drive air pressure to the handpiece with an
adjustment screw for each handpiece.
SYRINGE FLOW CONTROLAdjusts the air
and water flow from the three-way syringe.
AUTOMATIC HANDPIECE HOLDER
Shuts off air and water to the handpiece when it is in the
HANDPIECE TUBING FLUSH SYSTEM
Some newer models of dental units have a handpiece
tubing flush system that quickly and thoroughly
flushes the handpieces to wash away contaminants
accumulated in the handpiece and tubing. This system
saves wear on the handpieces by sending water directly
to the handpiece, and bypassing the control block and
not requiring the handpiece turbine to operate. Flush
the handpieces at the beginning of each day for 1