The purpose of this study was to measure the degree of anesthesia obtained with the mylohyoid nerve block and the combination mylohyoid nerve block/conventional inferior alveolar nerve (IAN) block in mandibular teeth.With the use of a repeated-measures design, 30 subjects randomly received each of 3 combinations of injections at 3 separate appointments. The combinations were as follows: mylohyoid nerve block (1.8 mL of 2% lidocaine with 1:100,000 epinephrine) + IAN block (3.6 mL of 2% lidocaine with 1:100,000 epinephrine); mock mylohyoid nerve block + IAN block (3.6 mL of 2% lidocaine with 1:100,000 epinephrine); mylohyoid nerve block (1.8 mL of 2% lidocaine with 1:100,000 epinephrine) + mock IAN block. The mylohyoid injections were aided by the use of a peripheral nerve stimulator. Mandibular anterior and posterior teeth were blindly tested with a pulp tester at 4-minute cycles for 60 minutes postinjection. Anesthesia was considered successful when 2 consecutive 80 readings were obtained.One hundred percent of the subjects had lip numbness with the mylohyoid nerve block + IAN block and mock mylohyoid nerve block + IAN block techniques. For these 2 techniques, anesthetic success rates were higher in posterior teeth (73% to 93%) than in anterior teeth (33% to 60%). There were no significant differences (P > .05) between the 2 techniques. The mylohyoid nerve block + mock IAN block technique resulted in a very low success rate (0% to 17%) and was significantly different (P < .05) from the mylohyoid nerve block + IAN block technique.The results of this study suggest that the mylohyoid nerve block does not by itself predictably provide pulpal anesthesia in mandibular teeth and does not significantly enhance pulpal anesthesia when administered in combination with the IAN block.