Objective Measurements of Pulpal Anesthesia with a Novel Topical Anesthetic

Objectives: Tetracaine anesthetic paste (6%;TAP) is a newly developed tetracaine- and propylene glycol-based topical anesthetic. The aim of our study was to determine the efficacy of relieving electric pulp-tester induced pain with TAP on healthy human teeth.

Methods: Study subjects (n=31) who met the inclusion criteria were randomly assigned to one of the following treatments: 1)tetracaine, 2)benzocaine 20%, or 3)placebo (TAP without tetracaine).  Baseline pulpal pain scores were measured with a digital, electric pulp tester by asking subjects to indicate when pain was first felt.  Twenty-five mg of one of the treatments was applied to the buccal and palatal mucosa of tooth #6 for ten minutes.  After ten minutes, the treatment was wiped off, rinsed with water and was re-tested with the pulp tester and every five minutes thereafter.  The subject and the investigator who performed the pulp testing had no knowledge of the treatment.  Each reading was normalized to each subject’s baseline response.

Results: Normalized baseline pulpal responses were doubled in 62.5% of TAP-treated subjects (10/16) and 37.5% (6/16) of TAP-treated subjects reached the maximum current possible of the pulp tester, whereas only 8.3% (1/12) of benzocaine-treated subjects doubled the baseline response and no benzocaine-treated subjects reached the maximum of the pulp tester.  One subject in the placebo group (1/3) doubled the baseline response and no participant reached the maximum of the pulp tester.  Mean +/- SE normalized responses at 10, 15, and 20 minutes were 1.44+/-0.1, 3.3+/-0.9, and 1.5+/-0.2 for TAP treatment, and 1.0+/-0.1, 0.99+/-0.1, and 0.99+/-0.1 for benzocaine-treated subjects.  Statistical comparisons between TAP- and benzocaine-treated subjects showed significantly increased anesthesia in TAP-treated subjects at 15 and 20 minutes (p<0.0004 and p<0.02, respectively; Wilcoxon Rank-Sum test).

Conclusions: Our results indicate that TAP reduced pulpal nociception significantly better than benzocaine and clinical indications for TAP need to be investigated.