Pain is now widely
recognized as a complex interaction of physical and psychological factors
associated with actual or potential
tissue damage. There is no question that pain often serves a useful protective
function. For example, withdrawing from a hot stove or sharp object before
significant injury can occur happens almost immediately and without conscious
control. Children afflicted with congenital analgia (ie, congenital insensitivity
to pain) experience frequent serious and often life-threatening injuries due to
a complete absence of pain sensation. The value of tooth pain before, during,
or after treatment is less obvious. Inflammatory mediators associated with pain
may also be observed with wound healing, but it is clear that successful
healing can occur without significant pain. The presence of pretreatment pain
is often a valuable diagnostic aid, as hyperalgesia and allodynia associated
with pulpal and periradicular inflammation allow more rapid and reliable
identification of the source of the pain. The following presentation highlights
several current techniques and strategies to manage pain related to endodontic
treatment.
Is it possible to
predict which patients are more likely to experience significant pain and
therefore manage them more effectively? While quality evidence is lacking, several
initial studies provide some guidance in this area. A consistent finding is
that the presence of significant preoperative pain is a strong predictor of
postoperative pain. Less certain predictors of postoperative pain include:
presence of multiple allergies (ie, atopy), apprehension or anxiety,
retreatment of a root canal, and a necrotic tooth with either a small
periradicular lesion or none at all.1,2 Pretreatment with nonsteroidal anti-inflammatory drugs (NSAIDs)3,4 and the use
of a long-acting local anesthetic5 are both useful strategies for
reducing postoperative pain. Ibuprofen remains the standard NSAID for
comparison purposes and is generally well tolerated by most patients. Clearly, a
history of allergy or hypersensitivity to any NSAID or the presence of certain
medical conditions (eg, active ulcers) would contraindicate the use of
ibuprofen. Approximately 400 mg of ibuprofen is equivalent to 10 mg of morphine.6
A recent review of all commonly available oral analgesics found that 100% of
patients taking 800 mg of ibuprofen had greater than 50% pain relief, and this
analgesic had, overall, the lowest number needed to treat (NNT=1.6), even when
compared to narcotic analgesics.7 An NSAID is most effective when
given either preoperatively or immediately postoperatively rather than waiting
until after pain is present.
Pulpal Anesthesia
Profound local
anesthesia is often an elusive goal when faced with an irreversibly inflamed
pulp, particularly with mandibular posterior teeth. Recent research suggests
that inflammation in the pulp causes secondary changes along the entire pathway,
from the peripheral site to the central nervous system. Routine local
anesthesia techniques may not be sufficient to provide profound pulpal
anesthesia in the presence of inflammation. Even in the absence of
inflammation, an inferior alveolar nerve block is only about 60% to 75%
effective.8 Lack of complete anesthesia may be acceptable for many
patients undergoing routine operative procedures, but profound pulpal
anesthesia is a prerequisite for root canal treatment on vital teeth.
Regardless of the inferior
alveolar nerve block technique of choice (eg, standard, Gow-Gates, Akinosi),
lip and tongue anesthesia does not guarantee pulpal anesthesia. Supplemental
buccal and lingual infiltration may help, but is often insufficient.
Intraligamentary injections can be effective if adequate back pressure is
obtained. An intrapulpal injection is usually effective but is also painful and
requires direct entry into the pulp prior to injection.
Interest in the use
of intraosseous (IO) injections has recently increased due to the availability
of easy-to-use, single-use devices. When used as a supplemental technique, IO
injections provide profound anesthesia in the majority of teeth that were not
already anesthetized by the standard nerve block technique.9 An IO
injection with a local anesthetic containing epinephrine will almost certainly
result in a transient tachycardia. In such instances, patients should be
advised that it is normal to experience a temporary increase in heart rate. Use
of a local anesthetic with vasoconstrictor for IO injections should be avoided
in patients with significant cardiovascular disease or those taking medicines
that would contraindicate the use of a vasoconstrictor. Adequate anesthesia can
be obtained with an IO injection of 3% mepivicaine without vasoconstrictor,10,11
although a slightly higher dose may be required and the duration of pulpal
anesthesia will be reduced to approximately 15 to 30 minutes.
Articaine (4% with
1:100,000 epinephrine) has been promoted as a more effective anesthetic,
especially when used for infiltration anesthesia. Recent research comparing 4%
articaine with 1:100,000 epinephrine to 2% lidocaine with 1:100,000 epinephrine
for mandibular infiltration tends to support this claim,12 although
it should be noted that the teeth in this study had normal (ie, noninflamed)
pulps. Additionally, neither anesthetic solution, when used in an infiltration technique,
was as effective as a standard inferior alveolar nerve block injection. When
used for a block injection or IO injection, 4% articaine with 1:100,000
epinephrine is essentially equivalent to 2% lidocaine with 1:100,000
epinephrine.13,14 Prior to placing the rubber dam and initiating
endodontic therapy, it is recommended that the tooth be tested with EndoIce or
similar coolant to confirm pulpal anesthesia.
(Continued from page 1 )
Postoperative Pain Management
The most effective
and predictable treatment for teeth with irreversible pulpitis is a pulpectomy
and the use of NSAIDs as needed.4 For teeth with a diagnosis of
acute irreversible pulpitis, the minimal treatment required to predictably
diminish postoperative pain is pulpotomy, with a complete pulpectomy preferred
if time permits or in the presence of apical periodontitis.15,16
Complete debridement of all canals is the emergency treatment goal for necrotic
teeth.
Intracanal
medications generally have no effect on postoperative pain,15
although there is limited evidence to suggest that intracanal steroids
introduced into the periradicular tissues through the canal space or direct
injection of an NSAID around the tooth may reduce the incidence of
postoperative pain.17,18 Systemic steroids may decrease pain of
inflammatory origin,19,20 although they are not routinely used in
most endodontic practices. Occlusal reduction is recommended, particularly if
the following conditions are present: vital pulp, percussion sensitivity,
preoperative pain, and/or absence of periapical radiolucency.2
Antibiotics are not indicated for the
treatment of vital teeth4 and only indicated for adjunctive
management of patients with abscessed teeth and the presence of systemic
complications.21
Although most
postoperative pain can be effectively managed with an NSAID only,22
occasionally the addition of a narcotic analgesic is beneficial. The
combination of an NSAID and a narcotic may have a synergistic analgesic effect.23,24
A short-term (ie, 24 to 48 hours), “by the clock,” alternating combination of
an NSAID and a narcotic may be considered for patients with severe pain.
Conclusion
Careful selection
of an effective analgesic regimen may alleviate the stress and anxiety
associated with endodontic therapy. This strategy, in addition to timely
pulpectomy/debridement, use of a preoperative NSAID and a long-acting local
anesthetic, and occlusal reduction, should result in effective pain management
for almost all patients.
*Director of
Postdoctoral Endodontics, University
of Illinois at Chicago, Chicago, IL.
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