procedures. Your role with this group ranges from
keeping an adequate number of rotary instruments in
the treatment room to changing them in the handpiece.
Basic Rotary Instruments
Rotary instruments, such as burs, have three basic
parts: head, neck, and shank (fig. 11-12). The head of
the bur is the working or cutting portion, which is made
in many sizes and shapes. The neck, which is the
narrow portion of the bur connects the shank and the
head. The part of the bur that fits into the handpiece is
the shank. The length of the shank depends on the
specific use of the bur, whereas the shape of the shank
is designed to fit into a specific handpiece.
We have already discussed the several types of
handpieces used in dentistry. Each rotary instrument is
used in a particular handpiece. To indicate in which
handpiece the rotary instruments function, they have
been classed as friction grip, straight handpiece, or
latch contra-angle handpiece types (fig. 11-13). The
friction grip (FG) instruments are abbreviated as FG
and are used in high-speed handpieces and friction grip
low-speed contra-angles. These burs have small,
smooth shanks that are held in the handpiece by
friction against a metal or plastic chuck, or by a
wrench-tightened metal chuck. Friction grip burs are
available in short shank and miniature (pediatric), as
well as the commonly used standard length.
Figure 11-12.Bur parts and basic shank designs.
Figure 11-13.Classification of rotary instruments
The straight handpiece rotary instruments are
abbreviated as (SHP). They are used in electric
straight handpieces and in slow-speed, air driven
straight handpieces. The shank on the straight
handpiece instruments is larger in diameter than the
FG shank and at least twice as long.
The latch contra-angle handpiece instrument is
identified as angled handpiece (AHP) or latch-angle
(LA). This instrument is used in conventional latch
contra-angle handpieces. Common AHP rotary
instruments have a notched shanked with the same
diameter as the SHP instruments but are about half the
length. However, some AHP instruments are made
with short or long shanks.
Dental burs are available in many shapes and sizes.
The basic shapes of bur heads are the round, inverted,
pear-shaped, end and side cutting, straight/tapered
plain fissure, and tapered/straight crosscut fissure as
shown in figure 11-14.
Burs are made of either steel or carbide. Steel burs
are used in the slow-speed handpiece and dull after
only one use when cutting enamel of teeth and should
be discarded after use or when directed by the dentist.
Steel burs being used on dentin under slow-speed often
generate heat in the tissue of the tooth, causing
discomfort to the patient. The dentist will use the very
lowest speed to reduce the chance of heat and
High-speed handpieces use a carbide bur. Because
of its hardness, the carbide bur can be used many times
to cut hard enamel tooth structure without becoming
dull. However, carbide burs are brittle and have a
tendency to fracture under pressure. The carbide bur
operates most efficiently at high speeds with light
TYPES, USE, AND MAINTENANCE OF
Several pieces of equipment are commonly used in
many dental specialties. These items include provider
and assistant mobile chairs, amalgamators, and visible
light curing units.
PROVIDER AND ASSISTANT MOBILE
Provider and assistant mobile chairs play an
important role in the practice of dentistry because of
techniques that require both the provider and assistant
to work from seated positions. The doctors or