Anatomical Considerations in Mandibular Anesthetic Block Injections

Inferior Alveolar and Lingual Nerve Blocks

Block of the inferior alveolar nerve, also known as a mandibular block, occurs at the mandibular foramen just before the inferior alveolar nerve enters it.

The mandibular foramen is situated on the medial aspect of the ramus of the mandible, in close association with the lingula and the sphenomandibular ligament.

The anesthetic agent should be delivered to this point by piercing the mucosa between the retromolar pad and the pterygomandibular fold, at the level of the occlusal plane of the three mandibular molars. Most of the anesthetic solution should be deposited here.

To anesthetize the lingual nerve, which lies close by, it is necessary to deposit solution just anterior and medial to the bony landmark. Anesthesia of the inferior alveolar and lingual nerves desensitizes the mandibular teeth and gingiva on that side.

Occasionally, the buccal nerve must also be blocked to provide anesthesia of the mandibular buccal mucosa and gingival.

(A) Illustrates needle placement of anesthesia of the inferior alveolar or mandibular nerve. (B) Illustrates the area anesthetized.

Clinical Considerations of Mandibular Nerve Block

One advantage to the mandibular nerve block is that it provides a wide area of anesthesia for working on more than one tooth during one appointment because it anesthetizes the inferior alveolar nerve, the incisive, mental, and commonly the lingual nerve on the mandibular quadrant. This would include the buccal mucoperiosteum anterior to the first molar. The buccal mucosa of the molars must be anesthetized with a buccal nerve block.

Disadvantages to the mandibular block include inadequate anesthesia (15%-20%); positive aspiration (10%-15%), highest of all intraoral anesthesia techniques; partial anesthesia due to inferior alveolar nerve/foramen anatomy; accessory innervation of the mandibular teeth; oral landmarks not consistent; and lower lip and tongue anesthesia discomforting to patients and dangerous for certain individuals.

Buccal Nerve Block (Long Buccal Nerve Block)

The buccal nerve crosses the anterior border of the ramus of the mandible at the level of the occlusal plane of the maxillary molars. Hence, this nerve may be anesthetized just lateral to the mandibular ramus. It is not necessary to anesthetize the buccal nerve unless anesthesia of the molar buccal gingiva is desired.

Clinical Considerations of Buccal Nerve Block

The success rate for buccal nerve anesthesia is nearly 100%; however, it can be uncomfortable if the needle penetrates the periosteum.

Because the tendon of the temporalis muscle may be penetrated, care must be exercised in depositing the anesthetic agent. Block anesthesia of the buccal nerve will anesthetize the buccal gingiva and mucosa of the mandibular molars.

 (A) Illustrates needle placement of anesthesia of the buccal nerve. (B) Illustrates the area anesthetized.

Mental Nerve Block

The mental nerve exits the mandibular canal via the mental foramen, located on the lateral aspect of the mandibular body. The foramen is located just below the second premolar, halfway between the gingival margin and the inferior border of the mandible.

Anesthetic solution should be introduced deep to the mucosa at the level of the second mandibular premolar, approximately at the fornix. Successful block of the mental nerve will anesthetize the facial periodontium of the mandibular premolars, canine, and incisors on one side, including adjacent gingival and alveolar tissues and the periodontal ligament. It should be remembered that if pulpal tissue is to be anesthetized, it will be necessary to block the incisive nerve at the mental foramen.

A) Illustrates needle placement of anesthesia of the mental nerve. (B) Illustrates the area anesthetized.

Clinical Considerations of Mental Nerve Block

The mental nerve and the incisive nerve are the terminals of the inferior alveolar nerve. The mental nerve serves the buccal mucosa anterior to the buccal foramen to the midline, and also the skin on the lower lip and chin. Hence, it is used most often when buccal soft tissue requires anesthesia for a dental procedure. As such, the mental nerve block is infrequently utilized in dental procedures.

Structures passing through in IDN block injections


video of IDN Block technique