The inferior alveolar nerve block (IANB)  does not always result in successful pulpal anaesthesia with studies noting failure rates between  44% and 81%.  Previous studies have suggested that preoperative medication might increase the success rate of the IANB.  The aim of this study was to determine the effect of the administration of the combination of preoperative ibuprofen/acetaminophen on the success of the IANB in patients with symptomatic irreversible pulpitis.

Patients with a mandibular posterior molar or premolar  with a  clinical diagnosis of symptomatic irreversible pulpitis who had not taken any analgesics for at least 8 hours were randomised to either the combination ibuprofen 800 mg/1000 mg acetaminophen or placebo 45 minutes prior to INAB. 15 minutes after INAB access cavity preparation was commenced.  Success was defined as no or mild pain (visual analog scale recordings) on access or initial instrumentation.

They found that the success rate for the IAN block was 32% for the combination ibuprofen/acetaminophen group and 24% for the placebo, with no significant difference (P =0.37) between the 2 groups.

They concluded:

For mandibular posterior teeth, a combination dose of 800 mg ibuprofen and 1000 mg acetaminophen given 45 minutes before administration of the IAN block did not result in a statistically significant increase in anaesthetic success in patients with symptomatic irreversible pulpitis.

Simpson M, Drum M, Nusstein J, Reader A, Beck M. Effect of combination of preoperative ibuprofen/acetaminophen on the success of the inferior alveolar nerve block in patients with symptomatic irreversible pulpitis. J Endod. 2011 May;37(5):593-7. Epub 2011 Mar 22. PubMed PMID: 21496654.

Previously  we reported on another study which did show a significant difference for INAB success with difference  medication so we await further work in this area for clarification.