Chapter 20

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.

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.

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.

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.

### Anatomy of the Trigeminal Nerve

#### General Considerations

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.

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 ...

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