Ultrasonic activation of internal bleaching agents

Cardoso M, Martinelli CSM, Carvalho CAT, Borges AB, Torres CRG. Ultrasonic activation of internal bleaching agents. International Endodontic Journal, 46, 40-46, 2013. Aim To evaluate the effectiveness of ultrasonic activation of bleaching agents during ex vivo internal bleaching. Methodology Fifty canine human teeth were artificially stained, root filled and divided into five groups (n = 10) that received SP sodium perborate plus deionized water (control group), CP 37% carbamide peroxide gel, CPUS 37% carbamide peroxide gel plus ultrasonic application, HP 35% hydrogen peroxide gel or HPUS 35% hydrogen peroxide gel plus ultrasonic application. In groups CP and HP, the bleaching agent was left inside the pulp chamber for three applications of 10 min. In groups CPUS and HPUS, the same process was performed, but ultrasonic vibration was applied to the bleaching agent by an alloy tip for 30 s, with 30 s intervals. Two sessions were performed. The colour was measured initially and after each session by an intraoral dental spectrophotometer. The variation (?) of the colour parameters based on the CIELab system L*, a* and b*, and the colour alteration ?E* were calculated after first and second section. Data were analysed by one-way anova and Tukey's test. Results There was no significant difference amongst groups for ?L*, ?a* and ?E*, but there was a significant difference for ?b* in the first and second sessions (P = 0.0006 and 0.0016, respectively). After the first session, ?b* was significantly greater for groups HP and HPUS, without a significant difference between them. For the second session, group HPUS had the greatest ?b* values, but they were similar to groups HP and SP; group CP had the lowest values, which were similar to groups CPUS and SP. Conclusion Ultrasonic activation of bleaching agents during ex vivo internal bleaching was no more effective than conventional internal bleaching procedures, without activation.