INFERIOR ALVEOLAR NERVE BLOCK (CONVENTIONAL MANDIBULAR BLOCK)

When deep operative or surgical procedures are undertaken for the mandibular primary or permanent teeth, the inferior alveolar nerve must be blocked. The supraperiosteal injection technique may sometimes be useful in anesthetizing primary incisors, but it is not as reliable for complete anesthesia of the mandibular primary or permanent molars.

Olsen reported that the mandibular foramen is situated at a level lower than the occlusal plane of the primary teeth of the pediatric patient.⁷ Therefore the injection must be made slightly lower and more posteriorly than for an adult patient. An accepted technique is one in which the thumb is laid on the occlusal surface of the molars, with the tip of the thumb resting on the internal oblique ridge and the ball of the thumb resting in the retromolar fossa. Firm support during the injection procedure can be given when the ball of the middle finger is resting on the posterior border of the mandible. The barrel of the syringe should be directed on a plane between the two primary molars on the opposite side of the arch. It is advisable to inject a small amount of the solution as soon as the tissue is penetrated and to continue to inject minute quantities as the needle is directed toward the mandibular foramen.

The depth of insertion averages about 15 mm but varies with the size of the mandible and its changing proportions depending on the age of the patient. Approximately 1 mL of the solution should be deposited around the inferior alveolar nerve (Figs. 13-1 and 13-2).

Figure 13-1 The mandible is supported by the thumb and middle finger, while the needle is directed toward the inferior alveolar nerve.

Figure 13-2 Anesthetic solution is deposited around the inferior alveolar nerve.

LINGUAL NERVE BLOCK

One can block the lingual nerve by bringing the syringe to the opposite side with the injection of a small quantity of the solution as the needle is withdrawn. If small amounts of anesthetic are injected during insertion and withdrawal of the needle for the inferior alveolar nerve block, the lingual nerve will invariably be anesthetized as well.

LONG BUCCAL NERVE BLOCK

For the removal of mandibular permanent molars or sometimes for the placement of a rubber dam clamp on these teeth, it is necessary to anesthetize the long buccal nerve. A small quantity of the solution may be deposited in the mucobuccal fold at a point distal and buccal to the indicated tooth (Fig. 13-3).

Figure 13-3 In anesthetizing the long buccal nerve, a small quantity of the solution may be deposited in the mucobuccal fold adjacent to the first permanent molar.

All facial mandibular gingival tissue on the side that has been injected will be anesthetized for operative procedures, with the possible exception of the tissue facial to the central and lateral incisors, which may receive innervation from overlapping nerve fibers from the opposite side.

INFILTRATION ANESTHESIA FOR MANDIBULAR PRIMARY MOLARS

Wright and colleagues have studied the effectiveness of injecting local anesthetic solution in the mucobuccal fold between the roots of primary mandibular molars.⁸ Based on observational data, little or no pain was experienced by 65% of the children during cavity preparation. It was also noted that children who demonstrate comfort at the time of injection are likely to exhibit no pain during successive procedures.

Oulis and associates⁹ reported very similar studies comparing the effectiveness of mandibular infiltration anesthesia to mandibular block anesthesia in children 3 to 9 years of age for restorative pulpotomy and extraction therapies in primary mandibular molars. Eighty-nine and 80 children, respectively, were included in their studies. Oulis and associates found that the two anesthesia techniques were equally effective for restorative procedures, but the mandibular infiltration technique was less effective than mandibular block for extraction and pulpotomy.⁹ In 1976 a new local anesthetic, articaine, was introduced in Europe and by 1983 it was in use in Canada. It was not available in the United States until 2000, by which time the preservative had been removed from the formulation, and it received Food and Drug Administration (FDA) approval. Articaine (Septocaine), manufactured by Septodont (http://www.septodontusa.com) underwent several research studies to test reliability and effectiveness, and became readily available and widely used. Articaine is unique among local anesthetics because it contains a thiophene group as well as both ester and amide groups. Articaine is an amide anesthetic (it has an amide intermediate chain) that is metabolized in the liver. The associated ester group also allows plasma metabolism via pseudocholinesterase, which purportedly increases the rate of breakdown and reduces toxicity. This difference in metabolism gives articaine the advantage of having a 30-minute half-life; lidocaine, for example, has a 90-minute half-life.^10–14

Sharaf¹⁵ demonstrated that behavior in young children can be adversely affected by the painful mandibular block. It is well known that articaine has a high bone penetrating ability, which suggests that it may be more successful as a locally injected infiltration. From these reports, one may infer that mandibular infiltration anesthesia may produce adequate anesthesia in mandibular deciduous molars for most restorative procedures.

INFILTRATION FOR MANDIBULAR INCISORS

The terminal ends of the inferior alveolar nerves cross over the mandibular midline slightly and provide conjoined innervation of the mandibular incisors. A single inferior alveolar nerve block may not be adequate for operative or surgical procedures on the incisors, even on the side of the block anesthesia. The labial cortical bone overlying the mandibular incisors is usually thin enough for supraperiosteal anesthesia techniques to be effective.

If only superficial caries excavation of mandibular incisors is needed or if the removal of a partially exfoliated primary incisor is planned, infiltration anesthesia alone may be adequate. Incisor infiltration is most useful as an adjunct to an inferior alveolar nerve block when total anesthesia of the quadrant is desired. In this case the infiltration injection is made close to the midline on the side of the block anesthesia, but the solution is deposited labial to the incisors on the opposite side of the midline. For example, if block anesthesia is used for the mandibular right quadrant, anesthetic solution is infiltrated over the left mandibular incisors by insertion of the needle just to the right of the midline diagonally toward the left incisors.

MANDIBULAR CONDUCTION ANESTHESIA (GOW-GATES MANDIBULAR BLOCK TECHNIQUE)

In 1973, Gow-Gates introduced a new method of obtaining mandibular anesthesia, which he referred to as mandibular conduction anesthesia.¹⁶ This approach uses external anatomic landmarks to align the needle so that anesthetic solution is deposited at the base of the neck of the mandibular condyle. This technique is a nerve block procedure that anesthetizes virtually the entire distribution of the fifth cranial nerve in the mandibular area, including the inferior alveolar, lingual, buccal, mental, incisive, auriculotemporal, and mylohyoid nerves. Thus with a single injection the entire right or left half of the mandibular teeth and soft tissues can be anesthetized, except possibly the mandibular incisors, which may receive partial innervation from the incisive nerves of the opposite side. Gow-Gates suggested that, once the technique is learned properly, it rarely fails to produce good mandibular anesthesia.¹⁶ He had used the technique in practice more than 50,000 times. The technique has become increasingly popular and is often referred to as the Gow-Gates technique.

The external landmarks to help align the needle for this injection are the tragus of the ear and the corner of the mouth. The needle is inserted just medial to the tendon of the temporal muscle and considerably superior to the insertion point for conventional mandibular block anesthesia. The needle is also inclined upward and parallel to a line from the corner of the patient’s mouth to the lower border of the tragus (intertragic notch). The needle and the barrel of the syringe should be/>