Achieving profound anesthesia in symptomatic irreversible pulpitis is a cornerstone in endodontic practice as literature states that a single inferior alveolar nerve block is ineffective in 30-80% of patients due to anatomical variations, blood flow, local tissue pH, central sensitization, psychological factors and various reasons.

In Dentistry, the combination of adjuvant with lignocaine has provided better anesthetic and analgesic effect to overcome the failure of anesthesia. Magnesium sulfate (MgSO₄) acts as an antagonist at the N-methyl D-aspartate (NMDA) glutamate receptor resulting in effective anesthesia. Hence, the aim of this prospective randomized double blind clinical controlled trial is to evaluate the onset, anesthetic efficacy, duration and post-operative analgesia of 2% lignocaine combined with and without magnesium sulfate in patients with symptomatic irreversible pulpitis and apical periodontitis.

After obtaining ethical clearance, 42 patients were randomly divided into 3 groups following block randomization. Group 1: 2% lignocaine (LA) (1.5mL), 2% LA with MgSO₄ (75mg)(0.15mL) and (150mg)(0.3mL) in Group 2 and 3 respectively. Pre-operative vitals and HP-VAS pain score were recorded. Consent forms were obtained from patients willing to participate in the study. 42 patients randomly received IANB injection of the experimental solutions. The onset of anesthesia was recorded by EPT at every one-minute interval. Once the tooth was anesthetized, access cavity was performed under isolation and anesthetic efficacy was recorded on the placement of first file. Subsequent root canal treatment was carried out. The duration of anesthesia was evaluated based on normalcy in lip numbness. The postoperative analgesia was examined at an interval of 2, 6, 12, 24 and 48 hours. All the data were compiled and non-parametric tests were employed for statistical analysis.

In this study group 3 (2% LA with 150mg MgSO₄) hastens the onset (1.29min) and produced better anesthetic efficacy (3.29 HP-VAS) compared to group 2 (2% LA with 75mg MgSO₄) (2.07min) (9.14 HP-VAS) and group 1 (2% LA) (3.29min) (35.79 HP-VAS). The duration of anesthesia was significantly higher in group 3 (247.07mins) when compared to that of group 2 and group 1. Group 3 showed improved post-operative analgesic efficacy at 6th hour when compared to the other 2 groups and postoperative analgesia was observed to be significantly similar in group 2 and group 3 after 24 hours.

 Within the limitations of this study, it can be concluded that 2% LA with MgSO₄ (150mg) as an adjuvant showed faster onset, pronounced anesthetic efficacy, marked duration of anesthesia and significantly higher postoperative analgesia than 2% lignocaine. MgSO₄ affirms to be a potent adjuvant with 2% lignocaine in subsiding the endodontic pain intra-operatively and post-operatively.