Post-operative analgesia of 2% lignocaine with or without magnesium sulfate for inferior alveolar nerve block in symptomatic mandibular molars - a randomized double blind controlled clinical trial.

Background: Single inferior alveolar nerve block is ineffective in achieving adequate pulpal anesthesia in 30-80% of patients due to anatomical variations, local tissue pH, central sensitization, and several factors. Various supplementary techniques and combination of adjuvants with lignocaine are used to overcome these failures. Magnesium sulfate (MgSO), one such adjuvant, acts at the N-methyl-D-aspartate glutamate receptor resulting in effective anesthesia. The aim of this prospective, randomized, double-blind, clinical controlled trial was to evaluate the onset, anesthetic efficacy, duration and post-operative analgesia of 2% lignocaine with and without the addition of MgSO in patients with symptomatic irreversible pulpitis and apical periodontitis.

Methods: Fourty-two patients were randomly divided into three groups: 2% lignocaine (group 1) and 2% lignocaine with MgSO (75 mg) and (150 mg) in groups 2 and 3, respectively. Pre-operative vitals and Heft Parker-Visual Analogue Scale (HP-VAS) pain scores were recorded. The onset of anesthesia, anesthetic efficacy, and duration of anesthesia were evaluated post administration of the local anesthetic solution. The post-operative analgesia was examined at intervals of 2, 6, 12, 24, and 48 h.

Results: Administration of 150 mg MgSO hastens the onset of anesthesia (1.29 min) and produces better anesthetic efficacy (3.29 HP-VAS) compared to group 2 (2.07 min and 9.14 HP-VAS) and group 1 (3.29 min and 35.79 HP-VAS), respectively. The duration of anesthesia was significantly higher in group 3 (247.07 min) compared to that of groups 2 and 1 (190 min and 110.21 min) with P < 0.05.

Conclusion: Combining 75 mg or 150 mg of MgSO with lignocaine is more effective than 2% lignocaine and 75 mg of MgSO is adequate for endodontic procedures.