Indications and Clinical Considerations
The inferior alveolar nerve block is useful in the diagnosis and treatment of pain involving the molars 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 molars are innervated primarily by the mandibular (inferior alveolar) nerve ( Figure 9-1 ). Because of the thicker mandibular bone, which supports the premolars, diffusion of local anesthetic with buccal fold block is limited, and blockade of the mandibular nerve before it enters the mandibular canal is required ( Figure 9-2 ). The lingual gingiva in the region of the lower molars is innervated by the lingual nerve (see Figure 9-2 ). Terminal branches of the buccal nerve pass through the buccinator muscles and provide innervations for the buccal mucosa in the region of the lower molars (see Figure 9-2 ). For satisfactory anesthesia to be provided to the lower molars, both the mandibular and lingual nerves as well as the buccal nerve need to be blocked ( Figure 9-3 ).
