Inferior Alveolar Nerve Block for Lower Premolar Teeth

Indications and Clinical Considerations

The inferior alveolar nerve block is useful in the diagnosis and treatment of pain involving the premolars of the lower jaw. This technique can provide much-needed emergency relief of dental pain while the patient is waiting for definitive dental treatment. It can also serve as a useful diagnostic maneuver when the clinician is trying to localize the nidus of pain that the patient perceives as dental in origin.

Dental pain is the result of irritation or inflammation of the nerves of the pulp and/or root of the tooth. Common causes of irritation or inflammation responsible for dental pain include infection, decay with resultant nerve exposure, gingival disease, plaque at or below the gum line, bruxism, injury, tumor, or tooth extraction. Less common causes include chemotherapy-induced odontalgia and barodontalgia. Pain involving the incisors or canine teeth may also be referred from other anatomic areas. Such referred pain may be indicative of temporomandibular joint dysfunction, sinus disease, abnormalities of the trigeminal nerve and its branches, and coronary artery stenosis.

Dental pain may range from a dull ache to severe, unremitting pain. Its onset may be insidious or acute. Dental pain is often worse when the affected tooth or teeth are exposed to hot or cold temperatures and when direct pressure is applied to the tooth or teeth when chewing. Tapping on the affected tooth or teeth may elicit an acute exacerbation of the pain. If significant inflammation or infection is present, rubor and color as well as swelling may be seen. Gingival bleeding or purulent drainage may also be present. It should be remembered that on occasion a severely compromised tooth causing a patient significant pain may appear completely normal.

Clinically Relevant Anatomy

The lower premolars are innervated primarily by the inferior alveolar nerve ( Figure 8-1 ). Fibers of the buccal nerve innervate the buccal gingiva; the lingual gingiva is innervated by the sublingual nerve. Because of the thicker mandibular bone, which supports the premolars, diffusion of local anesthetic with the buccal fold block is limited, and mental or mandibular nerve block is required. The mental foramen lies just inferior to and between the lower premolars ( Figure 8-2 ).