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gently manipulates the point of an explorer around the
inside edge of the band. This contours the marginal
ridge of the restoration and removes the excess
amalgam around the matrix band. The assistant will
pass the dentist hemostats or cotton forceps to remove
the wedge if one was placed. With the thumb or finger
over the occlusal surface of the restoration and matrix
band, the outer and inner nuts are turned
counterclockwise to loosen the retainer from the band.
After the retainer is removed, the remaining band is
carefully removed. A loose end of the band is grasped
with the hemostats or cotton forceps and gently rocked
back and forth until the band comes out of the
interproximal space. Remove the band from the other
interproximal space in the same manner.
PIN AMALGAM SET
Extensive decay or a cusp fracture results in the
loss of a major portion of the tooth structure. To
restore such a tooth to its former healthy condition, the
dentist may choose to rebuild the tooth. If the tooth is a
posterior one, the dentist may use the pin amalgam
technique. For a pin amalgam restoration, the dentist
uses specific instruments. The pin amalgam
instruments are packaged in kits in which pin burs
(drills), self-threading pins, and pin (hand) wrenches
are precision matched. It is extremely important to
keep the set together since there are a large variety of
types and sizes. The pins are placed with a hand
wrench in the tooth preparation to anchor the amalgam
or restorative material in place (fig 4-32). A pin
bender is frequently used to bend or slightly adjust the
position of inserted pins. Follow the manufacturer's
instructions before handling these materials.
FOUR-HANDED DENTISTRY
The goal of four-handed dentistry is to allow the
dentist and assistant to function as a team in a seated
position with maximal efficiency and minimal strain.
Four-handed dentistry, as it has been developed, not
only increases productivity, but also reduces stress and
fatigue on the provider and assistant. Four-handed
dentistry can be used in all of the specialty areas, and in
operative dentistry. It is discussed here because
instrument exchanges in operative dentistry require
you to perfect this task. To be an effective dental
assistant in four-handed dentistry, you must know the
correct zones and positions that you are in and where
you are in relation to the patient and dentist. Also
correct passing and receiving of instruments and
materials to the dentist is a task that must be practiced
to work efficiently with the dentist.
ZONES AND POSITIONS
The position of the patient is determined by the
procedure to be performed. Most dental treatment is
provided with the patient in the supine position. Once
the patient has been seated, the dentist and the assistant
should place themselves in the proper positions for
treatment. These positions are best understood by
relating them to a clock. In the clock concept, an
imaginary circle is placed over the dental chair, with
the patient’s head at the center of the circle. The circle
is numbered like a clock with the top of the circle at 12
o'clock. The clock, as shown in figure 4-33, is divided
into four zones of operation:
Static zone
Assistant's zone
Transfer zone
Operator's zone
The use of these zones is the key to the efficient
implementation of the principles of four-handed
dentistry. For right-handed dentists, seated to the
right of the patient, the operator's zone is between 8
and 11 o'clock, and the assistant's zone is between 2
Figure 4-32.—Using a hand wrench to place pins in a tooth
preparation.
Figure 4-33.—Zones of operation for four-handed dentistry.
4-15
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