BACKGROUND Achieving profound pulpal anaesthesia with an inferior alveolar nerve block (IANB) in lower molars suffering irreversible pulpitis is difficult and quite challenging. In many instances, supplemental anaesthesia is required during endodontic therapy. The present study was done to evaluate the efficiency of 2 % lidocaine and 4 % articaine comparatively, as an inferior alveolar nerve block (IANB) and supplemental infiltration buccally in providing complete mandibular molar anaesthesia. METHODS This is a randomized double-blinded study. Sixty patients were categorized randomly into test group (n= 30) and control group (n= 30). Patients in the test group were anaesthetized with 4 % articaine (1:100,000 epinephrine dilution), and those in the control group were anaesthetized with 2 % lidocaine (1:80,000 epinephrine dilution). The Heft-Parker visual analog scale (HP-VAS) was utilized for rating patient’s pain during the treatment procedure. In case of pain after IANB, a supplemental buccal infiltration was given with the same anaesthetic used for IANB. Complete pain absence or mild pain was regarded as an anaesthetic efficacy, and moderate to severe pain was regarded as an anaesthetic failure. Recorded data was analyzed using the chi-square test and two proportion Z test. The set significance level was 0.05. RESULTS After an IANB, observed anaesthetic success was 56 % in the articaine (test) group and that in the lidocaine (control) group was 33 %. After buccal infiltration, it was 92 % in the articaine group and 75 % in the lidocaine group. The difference was not found significant between the two groups statistically following IANB and infiltration buccally. The overall success of articaine was 96 %, and lidocaine was 83 %. CONCLUSIONS Compared to 2 % lidocaine, 4 % articaine was found more efficient in achieving profound pulpal anaesthesia in mandibular molars suffering irreversible pulpitis after IANB and buccal infiltration though the difference was insignificant statistically. KEY WORDS Articaine, Lidocaine, Inferior Alveolar Nerve Block, Buccal Infiltration, Heft-Parker Visual Analog Scale, Irreversible Pulpitis