Effects of the iontophoresis of lignocaine with epinephrine into exposed dentine on the sensitivity of the dentine in man

• 20% lignocaine + 0.1% epinephrine were applied to normal dentine by iontophoresis (120 μA, 90 s).
• The dentine was anaesthetized to probing and air-blast stimuli.
• There was also a fall in pulpal blood-flow.
• The epinephrine alone reduced pulpal blood flow but not the responses to the stimuli.
• The method can produce anaesthesia of dentine without an injection.

ObjectiveTo determine the effects of the iontophoretic application of lignocaine and epinephrine to exposed dentine on the sensitivity of the dentine in human subjects.DesignThe experiments were carried out on 13 healthy premolars (13 subjects) that were scheduled for extraction. Dentine was exposed at the tip of the buccal cusp by cutting a cavity which was etched with 35% phosphoric acid. The sensitivity of the dentine was tested with probing and air blast stimuli. The subject indicated the intensity of any pain produced with a score of 0–100. In 7 teeth, the cavity was filled with a solution containing 20% (w/v) lignocaine HCl and 0.1% (w/v) epinephrine HCl, and an iontophoretic current of 120 μA was passed for 90 s. The sensitivity of the dentine was tested before and immediately after the treatment and then at 10 min. intervals for 40 min. Pulpal blood flow was recorded at each stage. Control experiments were carried out on 6 teeth using a solution containing only the epinephrine.ResultsThe lignocaine plus epinephrine solution completely blocked the pain produced by both forms of stimulus immediately, and this continued for at least 40 min. It also produced an immediate fall in pulpal blood flow that also lasted for at least 40 min. The epinephrine solution had the same effect on pulpal blood flow but no effect on dentine sensitivity.ConclusionsThe topical application of 20% lignocaine and 0.1% epinephrine, with an iontophoretic current of 120 μA for 90 s, will anaesthetize exposed, normal, dentine.