Infiltration anesthetic technique has been proved to overcome the anesthetic failure caused by accessory nerve supply in adults. As described from this clinical study of patients with acute irreversible pulpitis, the use of retromolar canal (RMC) infiltration was found to boost the effectiveness of inferior alveolar nerve block (IANB) technique for numbing mandibular first molars.

To find the efficacy of RMC infiltration after the failure of IANB injections for irreversible pulpitis.

Fifty patients with acute irreversible pulpitis were given IANB injection. Lip numbness was considered as a sign of anesthesia, which was further assessed and confirmed via the pulp sensibility tests after 10 to 15 minutes. The occurrence, absence, or decrease in pain during access cavity preparation via the Heft-Parker visual analog scale was used to determine the success of the RMC infilteration.

After the use of IANB Injection, 7 patients did not suffer from pain as assessed by pulp sensibility tests and throughout the access cavity preparation. Pain relief was reported by 25 (58.1%) of the remaining 43 patients who had RMC infiltration injection. No change in pain was reported by 14 patients (32.5%). Also, the percentage of patients with decreased pain was higher as compred to that of other patients.

A combination of RMC infiltration and IANB significantly provided pain relief and enhanced the success of this anesthetic procedure for endodontic therapy in case of acute irreversible pulpitis.