Comparative study on anesthetic potency of dental local anesthetics assessed by the jaw-opening reflex in rabbits.

The potency of 4 local anesthetics to dental pulp was compared. Drugs were 4% articaine with 12 microgram/mL epinephrine (A12), 4% articaine with 6 microgram/mL epinephrine (A6), 2% lidocaine with 12.5 microgram/mL epinephrine (L), and 3% propitocaine with 0.03 IU/mL felypressin (P). Local anesthetics were injected into the dental root of the mandibular incisor. Electromyogram (EMG) of the digastric muscle was measured during the jaw-opening reflex induced by electrical stimulation. The disappearance of the EMG wave was judged as positive evidence of anesthesia. The determination of ED50 of the anesthetic was made by probit analysis. The ED50 of the A12 was minimal in all the tested anesthetics throughout the entire course. The potency in the A6 was 2.8 times that of the L. The potency of the A12 at the 15-minute measurement was 3.8 times that of the A6. The ED50 of the P was higher compared with those of the other 3 groups. It was concluded that articaine showed quicker onset than lidocaine and propitocaine and that there was a need to increase the dosage to attain a quick onset or to extend the duration.