RESUMO
AIM: This in vitro study assessed the efficacy and adverse effects of violet LED bleaching with or without bleaching agents. MATERIAL AND METHODS: Dental blocks (n=40) were randomly distributed in 4 groups: violet LED (VL), 35% hydrogen peroxide (HP35), the association of hydrogen peroxide 35% with violet LED (VHP35) and the association of hydrogen peroxide 35% with blue LED (BHP35). Specimens were analyzed for Vickers microhardness initially, immediately after and seven days after ending bleaching protocol. The color analysis of the specimens was evaluated for bleaching effectiveness (ΔE2000, ΔE1976) and whiteness index (ΔWID) with EasyShade spectrophotometer, before bleaching protocol and seven days after ending bleaching protocol. The mineral composition of the enamel was evaluated by percentage of phosphorus and calcium on the enamel surface with energy dispersive spectroscopy (EDS). The color and the microhardness data were analyzed using one-way ANOVA with post-hoc Tukey (α=0.05). RESULTS: The microhardness test showed a difference among the groups only immediately after the completion of the protocol, in which there was a reduction in the value for the groups HP35 from 277,36 ± 21,56 to 198,76 ±32,2 (p<0,01); and BHP35 from 261,14 ± 36,01 to 212,66 ± 25,99 (p<0,01), but the microhardness was reestablished after seven days. Regarding EDS analysis, a reduction in the mineral percentage immediately after bleaching with the use of VL was observed, however, after seven days it was reestablished. Regarding the color analysis, there was no difference among the groups evaluated. CONCLUSIONS: The use of VL was effective as a dental bleaching tool and did not adversely affect the enamel surface after seven days of the ending of the bleaching protocol.
