c. The Syringe. The syringe (side-loading cartridge syringe) is the only item in
the setup that will require autoclaving after each patient. This syringe is used to
administer local anesthetics. Syringe needles are the disposable type. The length and
gauge needle used will vary depending on the preference of the dental officer. You will
be handling two different needles: an infiltrative and a conductive needle. The infiltrative
needle is 13/16 inch long and is used for maxillary injections. It is used to anesthetize a
small area of possibly two or three teeth. The conductive needle is 1 3/8 inch long. Block
injections are made with this, anesthetizing an entire area.
d. Local Anesthetics. Currently, two types of local anesthetics are available
through routine supply: lidocaine hydrochloride (Xylocaine) with epinephrine (1:50,000
to 1:100,000) and mepivacaine hydrochloride (Carbocaine) without epinephrine. These
types can be identified by their stopper color and by the color of their containers. For
example: lidocaine hydrochloride with epinephrine, one part to fifty thousand, is
recognized by a green stopper and green stripe on the container; lidocaine hydrochloride
with epinephrine 1:100,000 has a red stopper and a red striped can; and mepivacaine
hydrochloride has a white stopper and a brown container. The epinephrine is the
controlling factor as to how long the anesthetic will last. The more epinephrine, the longer
the area will stay anesthetized. The epinephrine is a vasoconstrictor that causes the
tissue around the capillaries to swell and thus constricts the capillaries and slows the
blood flow. The decreased blood flow slows diffusion of the anesthetic throughout the
body, thus prolonging its action. It also aids in controlling bleeding.
e. Aspiration Required. The assembly and usage of the aspirating syringe is
quite simple. The syringe is equipped with a device enabling the dental officer to
determine if he is injecting into the blood stream. The accidental injection of the agent
into the circulatory system may produce undesirable symptoms or death. Notice the
thumb ring and the barbed plunger. The barb penetrates the rubber stopper of the
anesthetic cartridge, permitting aspiration when the dental officer retracts the syringe
plunger by means of the thumb ring.
f. Instrument Setup. For the instrument setup for local anesthesia, see figure
1-16.
MD0503
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