In-office Dental Bleaching: Effect of Agent Concentration and Light Activation

Objectives: Evaluated the effect of different bleaching agents and equipments for light activation on the effectiveness of in-office dental bleaching.
Methods: 140 dental slices of 6.00 X 6.00 mm from bovine incisors were stained in black tea, included in gray silicone and randomly divided into 7 groups (n=20), according to bleaching agent: 35% hydrogen peroxide (HP35) or 6% (HP6), and type of light: blue LEDs - 470 nm/Laser (A) or violet LEDs - 405 nm/Laser (V). The negative control group received no bleaching treatment (CN). Three bleaching sessions were performed, with two applications of bleaching agent per session. In each application, the bleaching agent was kept in contact with enamel surface for 12 minutes. Light activation was carried out for 6 minutes in each application. The effectiveness (ΔE) was measured by reflectance spectroscopy (Vita Easyshade) seven days after the end of treatment. Data were analyzed by two-way ANOVA with a significance level of 5%. Effectiveness was the dependent variable and the independent variables were bleaching agent and light equipment.
Results: The analysis resulted in statistical differences for bleaching agent (p<0.0001), light equipment (p<0.0001) and interaction bleaching agent*light equipment (p<0.039). Bonferroni post-test showed that CN and HP6 are similar and different from HP6A, HP6V, HP35, HP35A and HP35V.
Conclusions: The use of light activation is essential to the bleaching agent of low concentration be effective. When activated by blue or violet LED light, low concentration bleaching agent is as effective as traditional treatment.