Method: The experiments were carried out on 17 premolars which scheduled for extraction as part of orthodontic treatment. The study was approved by the University ethic committee. Dentine was exposed at the tip of the buccal cusp by cutting a cavity (diam. 3 mm, depth 3 mm) and etched with 35% phosphoric acid. The baseline pain sensation induced by probing and air blast was assessed on 10 cm Visual analogue scale (VAS). In group I, the cavity was filled with 2.5% bupivacaine with 1:1,000 epinephrine. Then, the iontophoresis device (Dentaphore-II) was used with currents of 0.12 mA for 90 sec. Pain assessment to both stimuli was done again every minute for 5 min and every 10 min for 30 min. Pulpal blood flow were also recorded with a laser Doppler flowmeter. In group II, the experiments were performed exactly the same as group I but the cavity was filled with distilled water.
Result: The means baseline VAS score caused by probing and air blast obtained from group 1 experiments were 6.33 ± 2.19 cm and 6.00 ± 1.81 cm, respectively. The corresponding value significant decreased to 1.47 ± 2.23 and 1.27 + 2.12 (p<0.05, 1 way RM ANOVA, Tukey test) respectively immediately after iontophoresis. The subjects did not feel any pain to both stimuli 4 min after iontophoresis and last for 30 minutes. In group II, distilled water application had no significant effect on the mean VAS caused by both form of stimuli.
Conclusion: Iontophoretic delivery of 2.5% bupivacaine with epinephrine through exposed dentine for 1.5 min produce pulpal anesthesia but had longer onset than lidocaine.