Indications and Clinical Considerations
The buccal fold injection technique is useful in the diagnosis and treatment of pain involving the molars of the upper 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. 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 upper molars and surrounding periosteum and buccal and gingival tissue are innervated by the superior alveolar nerve, which branches from the infraorbital nerve before it enters the orbital cavity. These branches travel downward along the maxillary tuberosity to provide innervation for the upper molars and the buccal gingiva and associated periosteum. The gingiva, mucosa, and periosteum of the adjacent palate are innervated by the greater palatine nerve ( Figure 6-1 ). The greater palatine nerve passes from the pterygopalatine fossa via the pterygopalatine canal through the pterygopalatine foramen (see Figure 5-3 ). In some patients an anatomic variation occurs, and the upper molars are innervated primarily by the middle alveolar nerves. This variation has little clinical import as far as the success of this block is concerned. The palate adjacent to the molars is innervated by the greater palatine nerve and in some patients by small anastomosing branches of the nasopalatine nerve (see Figure 5-3 ). The periosteum and bone that surround and support the roots of the molars are relatively thin and readily allow diffusion of local anesthetics injected in this region. For satisfactory anesthesia to be provided to the upper molars, three separate injections are usually required: (1) the buccal fold injection, (2) the tuberosity injection, and (3) the supplemental greater palatine nerve injection. Each injection is described in the following sections.
Technique
Buccal Fold Injection
The patient is placed in a supine position. If the more distal molars are to be blocked, it is important not to have the patient open the mouth too widely or the coronoid process of the mandible will move ventrally and block the injection site. A total of 4 mL of local anesthetic is drawn up in a 5-mL sterile syringe. The lip overlying the affected tooth is retracted, and a small amount of topical anesthetic such as viscous lidocaine or EMLA cream is applied to the alveolar sulcus with a cotton-tipped applicator. After topical anesthesia has been achieved, a 25-gauge, 1½-inch needle is inserted through the previously anesthetized area and advanced axially and slightly posteriorly toward the apex of the affected tooth. When the needle tip impinges on bone, it is withdrawn slightly out of the periosteum, and after gentle aspiration 1 to 2 mL of local anesthetic is slowly injected around the apex target area; the anesthetic will rapidly diffuse and anesthetize the pulp of the affected tooth ( Figures 6-2 and 6-3 ). It should be noted that unlike the previously described buccal fold injection techniques for the incisors, canines, and premolars, this technique yields relatively little anesthesia of the adjacent lip ( Figure 6-4 ).
