Impact of hydrogen peroxide activated by lighting-emitting diode/laser system on enamel color and microhardness: An in situ design

BACKGROUND: Hydrogen peroxide (HP) at lower concentration can provide less alteration on enamel surface and when combined with laser therapy, could decrease tooth sensitivity. This in situ study evaluated the influence of 15% and 35% HP gel activated by lighting-emitting diode (LED)/laser light for in-office tooth bleaching. MATERIALS AND METHODS: Forty-four bovine enamel slabs were polished and subjected to surface microhardness (load of 25 g for 5 s). The specimens were placed in intraoral palatal devices of 11 volunteers (n = 11). Sample was randomly distributed into four groups according to the bleaching protocol: 15% HP, 15% HP activated by LED/laser, 35% HP, and 35% HP activated by LED/laser. The experimental phase comprised 15 days and bleaching protocols were performed on the 2(nd) and 9(th) days. Surface microhardness (KHN) and color changes were measured and data were analyzed by ANOVA (α = 0.05). RESULTS: There were no significant differences in microhardness values neither in color alteration of enamel treated with 15% HP and 35% HP activated or not by LED/laser system (P > 0.05). CONCLUSIONS: Both concentrations of HP (15 or 35%), regardless of activated by an LED/laser light, did not affect the surface microhardness and had the same effectiveness in enamel bleaching.