Local anesthesia of the maxilla will diffuse
readily through the periosteum and bone to the
nerves supplying the teeth, but the greater
density of the cortical bone in the mandible makes
diffusion more difficult. Some lower front teeth
may be anesthetized by an infiltration injection,
but the lower posterior teeth will generally require
nerve block anesthesia. Techniques for the
administration of nerve block anesthesia are
described in the Cooke-Waite Manual of Local
Before administering an intraoral injection,
wipe the injection site free of saliva and debris.
Swab the area with a Betadine sponge. Whenever
possible, avoid multiple injections in the oral
cavity. By carefully analyzing the location of the
teeth you want to anesthetize, you will normally
be able to block the area with a single injection.
Place the patient in a recumbent or supine
position for the injection. Reassure the patient
about the procedure to help calm him or her and
to avoid syncope. Never leave a patient alone
following an injection. Do not inject into an area
of swelling and inflammation. When swelling or
other indication of soft tissue inflammation
exists, the nerve may be blocked central to the area
The most commonly used anesthetic for dental
injections is Iidocaine (HCL) or Xylocaine® in a
2 percent aqueous solution. Xylocaine with
1:100,000 epinephrine may be used to prolong the
anesthetic effect. Use a 23- to 27-gauge 1-inch nee-
dle for all infiltration injections; however, a 23-
to 25-gauge 1 5/8-inch needle may be required for
some regional blocks.
Xylocaine is a relatively nontoxic preparation.
The maximum safe dose for an adult is 300 mg.
Toxic reactions may be the result of either
exceeding the maximum safe dose or injecting the
anesthetic intravenously faster than the body can
detoxify it. Always remember to aspirate before
injecting the anesthetic. A toxic reaction to
Xylocaine may have a brief excitatory stage
followed by depression or may simply be
evidenced by respiratory and cardiac depression.
Cerebral anoxia may precipitate convulsions.
Most toxic reactions are mild and transitory. Place
the patient in a supine position, and ensure that
there is a clear airway and adequate oxygen.
Support the respiratory and cardiac functions
until the body can detoxify the drug, thus ending
the reaction. Unless an extreme overdose has been
administered, the reaction will be brief and
transitory and require no medications. Other
possible reactions to look for when administering
intraoral injections are hematomas, blanching of
the skin, temporary paralysis of facial muscles,
and sometimes loss of eye control and temporary
blindness. These reactions will usually disappear
as the drug is detoxified by the body.
ORAL DISEASES AND INJURIES
As is true of all diseases and injuries, the
symptoms discussed here refer to what the patient
describes and the signs pertain to what you
This is the most widespread chronic disease
of mankind. The most common cause of dental
caries is bacterial plaque. The plaque on a
tooth gives bacteria a place to breed. These
bacteria release acids and other toxins that attack
tooth enamel. This produces carious lesions
Dental caries destroys tooth tissues. Caries
begins in the enamel. Usually, it first appears as
a chalky white spot on the enamel. It may stop
there, but if it does not, it goes through the enamel
and into the dentin. As the caries goes farther
into the dentin, the tooth pulp may be affected.
Figure 2-6 shows how caries progresses into the
Figure 2-6.-The progress of caries: Caries in the enamel
(left); caries going through the enamel and into the
dentin (top); caries spreading along the dentin-enamel
junction and going through the dentin to involve the