For success (absence of pain), low-quality evidence suggests that 4% articaine, 1:100,000 epinephrine was superior to 2% lidocaine, 1:100,000 epinephrine for root treating of posterior teeth with irreversible pulpitis, and 2% lidocaine, 1:100,000 epinephrine was superior to 4% prilocaine plain when surgical procedures/periodontal treatment was provided. Moderate-quality evidence shows that 2% lidocaine, 1:100,000 epinephrine was superior to 3% prilocaine, 0.03 IU felypressin when surgical procedures were performed.Adverse events were rare. Moderate-quality evidence shows no difference in pain on injection when 4% articaine, 1:100,000 epinephrine and 2% lidocaine, 1:100,000 epinephrine were compared, although lidocaine resulted in slightly less pain following injection.Many outcomes tested our primary objectives in simulated scenarios, although clinical alternatives may not be possible.Further studies are needed to increase the strength of the evidence. These studies should be clearly reported, have low risk of bias with adequate sample size, and provide data in a format that will allow meta-analysis. Once assessed, results of the 34 'Studies awaiting classification (full text unavailable)' may alter the conclusions of the review.