Local Anaesthesia in  Paediatric Dentistry
Injectable Local Anaesthetic Agents

Amide local anaesthetics 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 anaesthetics in minutes. There is variation in duration between anaesthetics, pulp and soft tissue, and maxillary infiltration and mandibular blocks.

The duration of pulpal anaesthesia for bupivacaine (90+ minutes) is greater than lidocaine (60 minutes) and articaine (60-75 minutes) and is also greater for soft tissue (240-720 minutes) compared to lidocaine and articaine (180-300 minutes). There are no procedures in paediatric dentistry that warrant 1.5 hours of pulpal anaesthesia and over 4 hours of soft tissue anaesthesia. 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 paediatric patients and those patients with special needs.⁴

Another difference among injectable anaesthetic agents is the maximum recommended doses. This is extremely relevant in paediatric dentistry where there is a wide variation in weight between patients and thus not all patients should receive equal amounts of local anaesthetic for the same procedure. Table 2 summarizes the maximum recommended doses of local anaesthetic agents as per the American Academy of Paediatric Dentistry (AAPD) Guidelines.

Note the AAPD maximum recommended dosages differ from the manufacturer’s maximum recommended dosages as illustrated in Table 3.

Using the AAPD maximum recommended dosages (Table 2), one can calculate the maximum recommended dosage and amount of local anaesthetic agent for patients of specific weight and type of anaesthetic. 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 anaesthetic solution in a 1.8cc cartridge of anaesthesia; lidocaine contains 36 mg and mepivacaine contains 54 mg.

Table 4 provides an quick dosage approximation and amount of local anaesthetic for patients of specific weight and type of anaesthetic.

The maximum amount of local anaesthetic agent needs to be reduced if the patient is receiving a supplementary dose of enteral or parenteral sedative agent for behaviour 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 Anaesthesia).