Local prophylactic benadryl injections in an attempt to reduce postinstrumental pain.

This study was done to determine the clinical efficacy of a 15-mg diphenhydremine hydrochloride (Benadryl) local injection as a prophylactic treatment in the prevention of pain resulting from initial instrumentation of necrotic teeth. A double-blind study comprised of 37 subjects, each with one nonvital maxillary tooth, was completed in which patients were divided into two equal groups. The experimental group received a local anesthetic of 3% Carbocaine, followed by an additional injection of the antihistamine. The control group received the local anesthetic and an equivalent quantity of sterile saline. Patients recorded their pain levels at various time intervals: preoperatively, immediately postoperatively, and at 3, 7, 12, and 24 h postoperatively. Graphic analysis using a Quatro-Pro spread sheet program showed that there were no significant differences between the groups pain scores. However, there was a correlation between pain and time elapsed after procedure. In both groups, postoperative pain appeared to increase from 3 to 7 h and decrease from 7 to 24 h.