How To Do an Inferior Alveolar Nerve Block

Fracture (of mandibular bone, alveolar ridge, teeth)

Dental caries Caries Caries is tooth decay, commonly called cavities. The symptoms—tender, painful teeth—appear late. Diagnosis is based on inspection, probing of the enamel surface with a fine metal instrument... read more

Dry socket Postextraction alveolitis (dry socket) Postextraction problems are a subset of dental emergencies that require immediate treatment. These problems include Swelling and pain Postextraction alveolitis Osteomyelitis Osteonecrosis of the jaw read more

Dental abscess Complications Pulpitis is inflammation of the dental pulp resulting from untreated caries, trauma, or multiple restorations. Its principal symptom is pain. Diagnosis is based on clinical findings, and results... read more (only if the abscess is distant from the nerve block site)

Laceration (mucosa, lower lip, skin of chin)*

Allergy to the anesthetic agent Local anesthesia for laceration treatment Lacerations are tears in soft body tissue. Care of lacerations Enables prompt healing Minimizes risk of infection Optimizes cosmetic results read more or delivery vehicle (can usually choose different anesthetic)

Absence of anatomic landmarks needed to guide needle insertion (eg, due to trauma)

Infection in the path of needle insertion: Use procedural sedation or other anesthesia.

Coagulopathy*: When feasible, correct prior to procedure.

Pregnancy: Avoid treatment in the 1st trimester if it can wait.

Allergic reaction to the anesthetic

Toxicity due to anesthetic overdose (eg, seizure, cardiac arrhythmias)

Intravascular injection of anesthetic/epinephrine

Hematoma

Neuropathy

Spread of infection, by passing the needle through an infected area

Anesthetization of branches of facial nerve (cranial nerve VII) due to excessively posterior needle placement

Failure to anesthetize

Needle breakage and loss of needle within soft tissues

Dental chair, straight chair with head support, or stretcher

Light source for intraoral illumination

Nonsterile gloves

Mask and safety glasses, or a face shield

Gauze pads

Cotton-tipped applicators

Dental mirror or tongue blade

Suction

Topical anesthetic ointment* (eg, lidocaine 5%, benzocaine 20%)

Injectable local anesthetic such as lidocaine 2% with epinephrine† 1:100,000, or for longer duration anesthesia, bupivacaine 0.5% with epinephrine† 1:200,000

Dental aspirating syringe (with narrow barrel and custom injectable anesthetic cartridges) or other narrow barrel syringe (eg, 3 mL) with locking hub

25- or 27-gauge needle: 3-cm long for nerve blocks

Document any preexisting nerve deficit before doing a nerve block.

Sedation may be needed for patients unable to cooperate with the procedure.

Nerve block may fail if the anesthetic is not placed sufficiently close to the nerve.

Use a new needle with each attempt (the previous needle may have become blocked with tissue or blood, which would thus obscure inadvertent intravascular placement).

Stop the nerve block procedure and use a different method of anesthesia if you are unsure where the needle is or if the patient is uncooperative.

The inferior alveolar nerve is a branch of the mandibular nerve, which is the 3rd branch of the trigeminal nerve.

The inferior alveolar nerve travels inferiorly and anteriorly on the medial side of the mandibular ramus. The nerve, accompanied by the inferior alveolar artery and vein, enters the mandibular foramen near the midpoint of the ramus. From this point, the nerve runs within and innervates the body of the mandible; a terminal branch, the mental nerve, reemerges through the mental foramen in the premolar region to innervate the lower lip and chin, as well as the lateral mucosa/gingiva overlying the lower incisor teeth, canine, and first premolar. After this branching, the inferior alveolar nerve continues anteriorly as the incisive nerve, to innervate the remaining teeth and bone anterior to the mental foramen up to the midline.

The lingula is the bony protuberance at the anterior margin of the mandibular foramen.

The coronoid notch (retromolar fossa) is the concavity of the anterior edge of the ramus, located posterior to the molars.

The pterygomandibular triangle is a fatty space bordered laterally by the coronoid notch, and medially by the pterygomandibular raphe.

The pterygomandibular raphe is a thin vertical band (a visible tendinous line where the buccinator and the superior pharyngeal constrictor muscles join) that borders the pterygomandibular triangle medially.

The needle is inserted posterolaterally into the pterygomandibular triangle, parallel to and about 1 cm above the mandibular occlusal plane. The needle will encounter resistance as it passes through muscle and connective tissue.

The anesthetic is ideally placed superiorly and posteriorly adjacent to the lingula (ie, just above the mandibular foramen).

The lingual nerve (also a branch of the mandibular nerve) runs near the injection zone and is typically anesthetized incidentally to the inferior alveolar nerve block.

Position the patient slightly inclined (semi-recumbent sitting position), with the occiput supported and the mouth opened wide, such that the injection site (medial side of the ramus) is accessible.

Right-handed operators should stand on the patient's right and left-handed operators on the patient's left.

Wear nonsterile gloves and a mask and safety glasses, or a face shield.

Use gauze to thoroughly dry the pterygomandibular triangle. Use suction as needed to keep the area dry.

Apply a small amount of topical anesthetic with cotton-tipped applicators and wait 2 to 3 minutes for the anesthesia to occur.

Instruct the patient to open the mouth comfortably wide.

Place the tip of your thumb or forefinger into the coronoid notch, to help visualize the vertical height at which the needle will enter, and retract the cheek to expose the pterygomandibular triangle.

Place and maintain the barrel of the syringe over the contralateral lower 1st and 2nd premolars.

Keep the needle parallel to—and about 1 cm above—the mandibular occlusal plane, at the vertical plane of the coronoid notch.

To establish the correct angle of approach and entry point, rest the side of the needle tip against the lateral edge of the pterygomandibular raphe, such that the tip now aims into the pterygomandibular triangle, with the bevel facing the ramus. Maintain this angle of insertion as you advance the needle.

Advance the needle tip slightly into the mucosa. Aspirate, to rule out intravascular placement, and inject a few drops of anesthetic to relieve the pain of the needle insertion itself. Repeat these small injections after incremental advancements of slightly < 1 cm.

If the patient experiences a sudden, sharp paresthesia, reassure the patient that means the needle is in the right spot. Slightly withdrawing and then redirecting the needle may relieve this sensation, but maintain direction toward the medial ramus and mandibular foramen.

Advance the needle until it is stopped by the ramus (typically after about 2 to 2.5 cm of insertion) and withdraw needle 1 mm away from bone.

If the needle does not hit mandibular bone, it may be too far posterior (eg, into the parotid). Withdraw the needle and redirect it (more anteriorly/laterally).

Once contact with the ramus is made, withdraw the needle 1 mm away from the bone.

Aspirate, to rule out intravascular placement.

If aspiration reveals intravascular placement, withdraw the needle 2 to 3 mm, then re-aspirate prior to injection.

Slowly inject about 2 to 4 mL anesthetic, but leave about 0.5 mL in the syringe to block the buccal nerve.

Withdraw the syringe and reinsert it just anterior and lateral to the anterior edge of the ramus at the level of the occlusal surface of the most posterior molar. Advance the needle posteriorly about 3 to 5 mm. Aspirate, to rule out intravascular placement, and inject about 0.25 mL of anesthetic.

Massage the injection sites to hasten the onset of anesthesia.

Have the patient rest, with mouth relaxed, while awaiting onset of anesthesia (5 to 10 minutes).

To minimize the risk of needle breakage, do not bend the needle prior to insertion, do not insert the needle to its full depth (ie, to the hub), and instruct the patient to remain still, with the mouth wide open, and resist grabbing your hand.

4% Articaine with epinephrine 1:100,000 may be used for supraperiosteal infiltration How To Do a Supraperiosteal Infiltration Supraperiosteal infiltration anesthetizes single teeth and is used to anesthetize maxillary teeth in adults and any tooth in children. Supraperiosteal infiltration is not effective for teeth... read more , but it is not recommended for nerve block procedures, due to a reported risk of protracted lingual nerve paresthesia.

Distraction techniques (eg, talking to the patient or having the patient hold someone else's hand) may help to reduce patient anxiety.

Inject the local anesthetic solution slowly (30 to 60 seconds) to reduce the pain of injection.