Comparative evaluation of 1.8 mL and 3.6 mL of 2% lidocaine with 1:200,000 epinephrine for inferior alveolar nerve block in patients with irreversible pulpitis: a prospective, randomized single-blind study.

INTRODUCTION: There is a decrease in the anesthetic efficacy of inferior alveolar nerve blocks in patients with irreversible pulpitis. It was hypothesized that the increasing the volume of anesthetic solution may improve the success rates of dental pulp anesthesia in patients with pulpal pain.

METHODS: Fifty-five adult volunteers, actively experiencing pain, participated in this prospective, randomized, single-blind study. The patients were divided into 2 groups on a random basis and received an inferior alveolar nerve block with either 1.8 mL or 3.6 mL of 2% lidocaine with 1:200,000 epinephrine. Endodontic access preparation was initiated after 15 minutes of the initial IANB. Pain during treatment was recorded using the Heft-Parker visual analog scale (HP VAS). The primary outcome measure, and the definition of "success," was the ability to undertake pulp access and canal instrumentation with no or mild pain (HP VAS score <55 mm). Statistical analysis was performed using the chi-square test.

RESULTS: All patients included in the final analysis had profound lip anesthesia. There were no significant differences in sex, age, or preoperative pain scores of the experimental groups. IANBs of 1.8 mL lidocaine with epinephrine had a success rate of 26%, whereas the administration of 3.6 mL had a 54% success rate. The difference was statistically significant.

CONCLUSIONS: Increasing the volume of 2% lidocaine to 3.6 mL improved the success rate as compared with 1.8 mL but did not give a clinical success rates of 100%.