Evaluation of ultrasound and light sources as bleaching catalysts - an in vitro study.

Purpose: To evaluate the efficacy of tooth bleaching with high concentration agents, varying the catalyst sources and exposure times.

Materials and methods: Stained human third molar fragments were randomized and placed into 8 groups (n = 5). G1: Whiteness HP Maxx (FGM, Joinville, SC, Brazil) 35% (HP)/5 min on enamel surface without external catalyst source; G2: HP/15 min without external catalyst association; G3: HP/5 min with Quartz Tungstein Halogen (QTH: Optilux 501C, Demetron/Kerr, Danbury, CT, USA) as a catalyst; G4: HP/15 min with QTH as a catalyst; G5: HP/5 min with LED/laser as a catalyst; G6: HP/15 min with LED/ laser as a catalyst; G7: HP/5 min with ultrasound as a catalyst; G8: HP/15 min with ultrasound as a catalyst. The efficacy of bleaching was measured using a spectrophotometer (initial fotoreflectance analysis, after artificial staining with black tea, and after each of the bleaching sessions). Three bleaching sessions were performed. Data were submitted to Analysis of Variance and Tukey-Kramer tests (P < 0.05).

Results: No significant differences were found between the catalyst sources as related to the factor of exposure time and within each evaluation time. For the 15 min exposure, the best result was achieved in the second bleaching session, except for the LED/laser group. For the 5 min exposure, the best result was achieved in the third session, except for ultrasound. The 15 min of exposure time showed higher reflectance than 5 min for LED/laser and ultrasound in all bleaching sessions and for halogen in the second bleaching session.

Conclusion: Light sources did not increase the catalytic efficiency of bleaching, and allowing a longer time for gel exposure on the enamel achieves faster results.