Bleaching effect of violet LED of 405-410 nm on stained endodontically treated teeth

Aim: To evaluate in vitro the whiteness index (WID) and the whiteness index variation (ΔWID), as well as the color stability of stained endodontically treated teeth after bleaching with violet LED (VL) and with hydrogen peroxide 35% (HP) associated or not to VL.

Methods: Twenty-four lower incisors were selected. The color was measured using a spectrophotometer at the following times: baseline, after staining, bleaching, and thermocycling, to determine the whiteness index and variation (WID and ΔWID). For the staining process, the teeth were immersed in human blood and centrifuged. After biomechanical preparation, the specimens were distributed into three groups (n = 8): control group (HP); violet LED (VL); and HP 35% + VL (HP+VL), and one session was performed for both bleaching procedures every week for three weeks, followed by thermocycling, where 10,000 cycles were performed. After color analysis, the data obtained were submitted to statistical analysis (RM ANOVA, p < 0,05).

Results: The staining of the teeth reduced the WID values for all experimental groups compared to baseline, and the bleaching protocols increased WID values, with the lowest WID values for group VL. There was no statistically significant difference after thermocycling for all groups compared to bleaching. Staining and thermocycling reduced the ΔWID values, and no difference was found between treatments at these assessment times. Bleaching increased the ΔWID values, with less pronounced changes in the VL group.

Conclusion: VL used alone has a lower bleaching effect compared to the bleaching treatment with HP, whether or not associated with VL, and the color stability was observed for all groups.