Injectable Local Anesthetic Agents

Amide local anesthetics available for dental usage include lidocaine, mepivacaine, articaine, prilocaine and bupivacaine. They differ from each other in their duration of action (Table 1) and the maximum dosage that may be safely administered to patients (Table 2).

Table 1 demonstrates the variation in duration of action of injectable local anesthetics in minutes. There is variation in duration between anesthetics, pulp and soft tissue, and maxillary infiltration and mandibular blocks.^4,5

Table 1. Duration of Injectable Local Anesthetics (in minutes).⁵

Table 1. Duration of Injectable Local Anesthetics (in minutes).⁵

The duration of pulpal anesthesia for bupivacaine (240 minutes) is greater than lidocaine (85 minutes) and articaine (90 minutes) and is also greater for soft tissue (340 minutes) compared to lidocaine and articaine (around 180 minutes). The prolonged time of duration of action increases the likelihood of self-inflicted, post-operative soft tissue injury and therefore the use of bupivacaine is not recommended in pediatric patients and those patients with special needs.^4,6

Another difference among injectable anesthetic agents is the maximum recommended doses. This is extremely relevant in pediatric dentistry where there is a wide variation in weight between patients and thus not all patients should receive equal amounts of local anesthetic for the same procedure. Refer to Table 1 that summarizes the maximum recommended doses of local anesthetic agents as per the American Academy of Pediatric Dentistry (AAPD) Guidelines.

Table 2. Dosage of local anesthesia per cartridge

Table 2. Dosage of local anesthesia per cartridge

Using the maximum recommended dosages (Table 2), one can calculate the maximum recommended dosage and amount of local anesthetic agent for patients of specific weight and type of anesthetic. For example:

To calculate the maximum amount of lidocaine 2% with 1:100,000 epinephrine and the number of cartridges that can be safely administered to a 30-pound patient, the clinician would perform the following calculations.

Thus, for a 30-pound child one can safely administer 1.67 cartridges of lidocaine 2% with 1:100,000 epinephrine.

To calculate the maximum amount of mepivacaine 3% plain and the number of cartridges that can be administered to a 30-pound patient the clinician would perform the following calculations.

Note the difference between the number of cartridges of lidocaine 2% and mepivacaine 3% that can be administered to a 30-pound child is due to the difference in the number of mg of anesthetic solution in a 1.8cc cartridge of anesthesia; lidocaine contains 36 mg and mepivacaine contains 54 mg. Thus the difference is due to varying concentration of the local anesthetic in the cartridge (1.8cc).

The maximum amount of local anesthetic agent needs to be reduced if the patient is receiving a supplementary dose of enteral or parenteral sedative agent for behavior management. The action of the sedative has an additive depressive effect on the central nervous and cardiovascular systems can initiate overdose consequences (see [Complications of Local Anesthesia](Complications of Local Anesthesia).