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The dentist can control the discomfort and
fear of local anesthesia. To ensure this outcome, it is necessary to
acknowledge many factors that have a significant influence on the degree of
pain during the administration of anesthesia. Some of the most important are
the patient's fear and anticipation of pain, perception of the needle and
syringe, technique and method used, condition of local tissue, and how well
the surface anesthesia is applied.
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Fear & Anticipation of Pain
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Most children consider the injection of anesthesia to be the
most undesirable intervention in the mouth.1,5 The
administration of local anesthesia is not only a stressful experience for
the patient, but also for the dentist. This is particularly the case when
the patient anticipates pain and unwillingly accepts the procedure of
anesthesia2,8,9 (Figure 55–1).
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There are two important aspects of administering painless anesthesia:
(1) communication and (2) technical. The occurrence of fear and a negative
experience of local anesthesia are most frequently found in
children.4,5
A calm and relaxed child is not only important for easier administration of
anesthesia but also for its success, that is, the effect of the
anesthetic.5,10,11 Psychological and pharmacologic
techniques can both be used to prepare the child for the administration of
local anesthesia.
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It should be stressed that a tense patient with an increased anticipation of
pain usually feels more intense pain during local anesthesia. Acquainting
the patient with surface (topical) anesthesia and the subsequent
anticipation that there will be no pain, can reduce the anticipation of pain
to a great extent. It is also important to stress that
suggestion can be used, with the aim of reducing
anticipation of pain. Suggestion and relaxation before the injection are
also important for the effect of the local anesthesia.5,11
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Verbal communication with the patient is
essential, and it should be maintained during the preparation and
administration of local anesthesia. It is important to emphasize that
surface anesthesia is given initially to ensure that all other procedures
are painless and pleasant. The patient should be encouraged while
administering the anesthesia. It should be stressed that this is done slowly
so that the administration is more pleasant and the anesthesia is maximally
effective.
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Conversation with the patient achieves better relaxation before and during
administration. If this is not possible by psychological means,
sedation (eg, nitrous oxide or midazolam) can be used.
However, sedation cannot replace local anesthesia; it is merely preparation
for easier and more successful administration of the local
anesthesia.11
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The main reason for fear of local anesthesia for most patients is the needle. In the case
of patients with strong fears or phobias of the needle, a needleless
technique of local anesthesia can be applied (eg, jet injection).
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During administration of needle injection anesthesia attention should be
paid to ensure that the discomfort of needle insertion is minimal or
completely prevented. Factors that influence the discomfort during the
penetration of the needle include diameter (gauge) of the needle, type of
needle, method of penetration through tissue, and quality of the topical
anesthesia of the mucous membrane. For instance, a thinner needle causes
less tissue trauma and less pain during penetration of the tissue
(Figure 55–2). Needles thicker than 27 gauge (optimal 27 and 30
gauge) are not recommended for use in children.11 Also, a
slow injection of small amounts of anesthetic is less painful to patients.
The site of the needle penetration should be prepared with the application
some form of surface anesthesia.
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Two features of local anesthetic have an influence on pain during
injection: temperature and pH. Prior to administering anesthesia, the local
anesthetic should be at room temperature. If the anesthetic is kept in a
refrigerator, it should be warmed up to body temperature prior to use by
holding it in the hand or better yet, in a warming
device10,11 (Figure 55–3).
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Local anesthetic that contains a vasoconstrictor (epinephrine) has an
appreciably lower pH than plain solutions of
local anesthetic. The lower the pH of the anesthetic, the
more painful is the injection. Consequently, the use of
local anesthetic without a vasoconstrictor is appropriate in children (eg,
plain solutions of mepivacaine or prilocaine). Indeed, studies have shown that pain associated with the
intraoral administration of local anesthesia can be significantly reduced if
a plain anesthetic without vasoconstrictor is used.10,12
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The level of anxiety in the patient before administration of local
anesthesia also depends to a large extent on the appearance
of the syringe. The traditional needle-injection assembly
automatically induces fear of dental treatment in a child. To avoid fear of
the needle or tension in the patient prior to anesthesia, it is possible to
successfully use jet injection in some areas.
This method then can be extended by additional administration of injection
anesthesia, if necessary.
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Infiltration anesthesia in loose tissue is less painful than for instance,
mandibular block anesthesia, in which the needle penetrates into the
denser tissues. In small children,
infiltration anesthesia in the mandible, can be used and thus avoid
mandibular blockade, which is more painful.
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Anesthesia of the palatal mucous membrane can be achieved by
the application of palatal nontraumatic injections (a combination with
intrapapillary anesthesia), application of jet injections, or
computerized anesthesia (eg, Wand method). Slow and steady injection is most
important to decrease pain, which is easiest to achieve by an
automated method. Alternatively objective assessment of injection
pressure can be used to avoid forceful, traumatic injection of local anesthetic.
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A combination of transcutaneous electrical nerve stimulation (TENS) and
infiltration anesthesia can reduce or completely eliminate pain from
injection (either infiltration or blockade).
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Condition of Local Tissue
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Administration of anesthesia into inflamed tissue may result in less
successful local anesthesia because of the high pH of the tissue and because
of other mediators of the inflammation. Nerve endings in an inflamed area
are hyperalgesic, and conduct painful impulses on minimal
stimulation.11 Consequently, the entrance of a needle and
administration of anesthetic into an inflamed area is considerably more
painful. Hyperalgesia of the nerves in the inflamed area can be remedied by the
administration of an anesthetic of greater concentration (eg, 4% instead
of 2% articaine, or 5% lidocaine).11
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Method of Administering Anesthesia
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Slow injection of the anesthetic is extremely important to decrease pain on injection.
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To decrease pain one
1.8-mL cartridge is injected over 1 to 2 minutes. Faster injection is painful because it results in
greater trauma injection pressure, and painful stretching of the local tissue.
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Topical anesthesia is a fundamental part of the administration of
infiltration local anesthesia because it has both psychological and pharmacologic
importance. Skillfully and patiently applied topical anesthesia can reduce or completely eliminate the pain from
the needle penetration (Figure 55–4).
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