Efficacy of adding dexmedetomidine to lidocaine to enhance inferior alveolar nerve block in patients with asymptomatic irreversible pulpitis: double-blind randomized clinical trial.

Objectives: This randomized, double-blind study was to determine whether dexmedetomidine (DEX) helped to improve the inferior alveolar nerve block's (IANB) success in patients with asymptomatic irreversible pulpitis (AIP). We hypothesized that adding DEX to lidocaine enhances the anesthetic effect of lidocaine to a satisfactory level by localizing anesthesia in a safer way.

Materials And Methods: Fifty adult volunteers with AIP in a first or second mandibular molar were randomly assigned to two groups to either receive 1.4 ml 2% plain lidocaine or 1.4 ml 2% lidocaine + 0.4 ml (40 μg) DEX, for standard IANB injection. Access cavity preparation initiated 10-15 min postinjection when the patient reported lower lip numbness and had two negative electric pulp tests (EPTs) with 5-min intervals. Heft-Parker visual analog scale (VAS) was used to report pain in three steps: during caries and dentin removal, access cavity preparation, and canal working-length determinations; EPT and VAS were analyzed by Friedman test; and success rates were analyzed by Mann-Whitney and Fisher's exact test using SPSS software version 20.

Results: Successful anesthesia (defined as no or mild pain during any of steps and no need for additional injection) is obtained in 12% of patients in the lidocaine group, while DEX-lidocaine group increased the success rate of IANB to 72% (p-value = 0.0001).

Conclusions: DEX significantly increases the anesthetic effect of lidocaine in IANB injection in patients with AIP.

Clinical Relevance: DEX would be a safe adjunct to lidocaine to increase the success rate in IANB and could be a suitable alternative for conventional vasoconstrictors in sensitive groups.