The role of temperature in the action of mepivacaine.

The role of temperature in the action of local anesthetics was studied in 20 healthy young volunteers with plain 3% mepivacaine injected periapically twice in their maxillary first premolar, the first time with the solution at a temperature of 20 degrees C and the second time at 4 degrees C. The pulpal response was measured with a pulp tester every minute. The onset of pulp anesthesia was found to be of no statistical difference between 20 degrees C and 4 degrees C. On the other hand, mepivacaine at a temperature of 4 degrees C was found to have a statistically significant longer duration of action. Our conclusion is that the drop in temperature of mepivacaine from 20 degrees C to 4 degrees C provides a longer duration of pulpal anesthesia.