The use of ultrasound for guiding needle placement for inferior alveolar nerve blocks

The degree of pulpal anesthesia obtained with an ultrasound-assisted inferior alveolar nerve block was compared to that obtained with a conventional inferior alveolar nerve block for mandibular teeth to determine whether needle placement assisted by ultrasound results in more successful anesthesia.

Through use of a repeated-measures design, each of 40 subjects randomly received an ultrasound-assisted inferior alveolar nerve block and a conventional inferior alveolar nerve block at 2 separate appointments. Mandibular anterior and posterior teeth were blindly tested by means of a pulp tester at 4-minute cycles for 60 minutes postinjection. Anesthesia was considered successful when 2 consecutive readings of 80 were obtained.

One hundred percent of the subjects had profound lip numbness with both the ultrasound-assisted inferior alveolar nerve block and the conventional inferior alveolar nerve block. For these 2 techniques, anesthetic success rates for individual teeth ranged from 38% to 92%. There were no significant differences (P > .05) between the 2 techniques.

It was concluded that accurate needle placement with ultrasound for the inferior alveolar nerve block did not result in more successful pulpal anesthesia in the mandible. Therefore, accuracy of needle placement is not the primary reason for pulpal anesthetic failure with this block.