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Oral surgical and dental procedures are routinely performed in an
outpatient setting. Regional anesthesia is the most common method of
anesthetizing the patient before office-based procedures. Many techniques
can be used to achieve anesthesia of the dentition and surrounding hard and
soft tissues of the maxilla and mandible. The type of procedure to be
performed as well as the location of the procedure determines the technique
of anesthesia to be used. Orofacial anesthetic techniques can be classified
into three main categories: local infiltration, field block, and nerve
block.
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The local infiltration technique anesthetizes the terminal nerve endings
of the dental plexus. This is indicated when an individual tooth or a
specific, isolated area requires anesthesia. The procedure is performed in
the direct vicinity of the site of infiltration.
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The field block anesthetizes the terminal nerve branches in the area of
treatment. Treatment can then be performed in an area slightly distal to the
site of injection. The deposition of local anesthetic at the apex of a tooth
for the purposes of achieving pulpal and soft tissue anesthesia is often
used by many dental and maxillofacial professionals. Although this is
commonly termed “local infiltration,” it is important to note that this is
a misnomer. Terminal nerve branches are anesthetized in this technique, and
it is therefore correctly termed a field block.
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A nerve block anesthetizes the main branch of a specific nerve, allowing
treatment to be performed in the region innervated by the nerve.1
This chapter reviews the essential anatomy of orofacial nerves and
details the practical approach to performing nerve blocks and infiltrational
anesthesia for a variety of surgical procedures in this region.
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Anatomy of the Trigeminal Nerve
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General Considerations
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Anesthesia of the teeth and soft and hard tissues of the oral cavity
cannot be achieved without knowledge of the trigeminal nerve (fifth cranial
nerve) and its branches. Regional, field, and local anesthesia of the
maxilla and mandible depend on the deposition of anesthetic solution near
terminal nerve branches or a main nerve trunk of the trigeminal nerve.
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The largest of all the cranial nerves, the trigeminal nerve gives rise
to a small motor root originating in the motor nucleus within the pons and
medulla oblongata, and a larger sensory root which finds its origin in the
anterior aspect of the pons. The nerve travels forward from the posterior
cranial fossa to the petrous portion of the temporal bone within the middle
cranial fossa. Here, the sensory root forms the trigeminal (semilunar or
gasserian) ganglion situated within Meckel's cavity on the anterior surface
of the petrous portion of the temporal bone. The ganglia are paired, one
innervating each side of the face. The sensory root of the trigeminal nerve
gives rise to the ophthalmic division (V1), the maxillary
division (V2), and the mandibular division
(V3) from the ...