Reversal of Pulpal and Soft Tissue Anesthesia by Using Phentolamine: A Prospective Randomized, Single-blind Study

By Elmore S, Nusstein J, Drum M, Reader A, Beck M, Fowler S.

Date: 01/2013
Journal: JOE


  • Compare the reversal of pulpal and soft tissue anesthesia when phentolamine was administered at 30 minutes versus 60 minutes after the administration of an inferior alveolar nerve (IAN) block.


  • N= 90 subjects
  • Exclusion criteria: Younger than 18 years of age; allergies to phentolamine, local anesthetics, or sulfites; pregnancy; history of significant medical conditions (ASA Class II or higher); taking any medications (over-the-counter pain relievers, narcotics, sedatives, antianxiety or antidepressant medications) that may affect pain assessment; active pathosis at the site of injection; and inability to give informed consent.
  • Positive/negative control: Mandibular contralateral canines
  • Control & Design: Crossover design – 1 group was given IANB w/2% Lidocaine, phentolaminemesylate at 30 min, followed by sham injection at 60 min.  The other group reversed the phentolamine and sham injections. Pulpal anesthesia was monitored utilizing EPT in 4 min cycles for each tooth tested. Soft tissue anesthesia was monitored by having the subject palpate their lip/tongue every 5 minutes.
  • Criteria of evaluation: Time to recovery of normal soft tissue was number of minutes from IANB to first of 2 consecutive confirmed palpation sensations. No response from subject at EPT reading of 80 confirmed pulpal anesthesia.


  • Significant differences were shown for return-to-normal sensation for lip and tongue when phentolamine was administered at 30 minutes, comparable to 60 minutes.

Clinical Significance:

Phentolamine could be beneficial as a safe alternative for patients desiring quicker recovery from anesthesia (less drooling, cheek/tongue biting, better smiling), however, operators will want to wait until the end of the appointment as results show pulpal anesthesia also recovers more quickly.