Indications and Clinical Considerations
This injection technique is useful in the diagnosis and treatment of pain involving the incisors or canine teeth 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, and tooth extraction ( Figure 7-1 ). 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 incisors and canine teeth are innervated by a branch of the incisive nerve, which is a distal branch of the inferior dental nerve. In most patients the nerve is covered by a thin layer of osseous lamina that allows easy diffusion of local anesthetic ( Figure 7-2 ). Occasionally the bone is too thick to allow rapid diffusion of local anesthetic, and a mental or mandibular nerve block will be required. It should be noted that fibers of the contralateral incisive nerve may cross the midline and confuse the clinical picture. The buccal soft issues in this region are innervated by branches of the mental nerve, whereas the lingual gingiva and associated periosteum are innervated by branches of the sublingual nerve ( Figure 7-3 ). Supplemental blockade of the mental and sublingual nerves may be required to provide complete anesthesia for the lower incisors and canine teeth.
