In vitro bleaching efficacy of violet LED associated with 10% hydrogen peroxide and 10% carbamide peroxide.

BACKGROUND: This in vitro study evaluated the efficacy and the effect over the dental enamel surface of violet LED dental bleaching associated to different concentrations of carbamide and hydrogen peroxide. METHODS: Human dental blocks (n = 100) were randomly distributed into 5 groups: 10% hydrogen peroxide (HP10), 10% carbamide peroxide (CP10), 10% hydrogen peroxide with violet LED (VHP10), 10% carbamide peroxide with violet LED (VCP10) and 35% hydrogen peroxide (HP35). The specimens were analyzed by Vickers microhardness test (n = 50) initially, immediately after and seven days after ending the bleaching protocol. For color analysis (n = 50), the specimens were evaluated for bleaching effectiveness (ΔE2000, ΔE1976) and whiteness index (ΔWID) with EasyShade spectrophotometer, before bleaching protocol and seven days after ending the bleaching protocol. The microhardness and color data were analyzed using one-way ANOVA with post-hoc Tukey test (α = 0.05). RESULTS: The microhardness values showed difference among the investigated groups only immediately after the end of the dental bleaching (p < 0.05), with reduction for the groups HP35 (p < 0.01) and HP10 (p < 0.05), however the microhardness values were reestablished after seven days. Regarding the color changes, a difference between VHP10 and the others groups evaluated for ΔE2000 and ΔE1976 index was observed (p < 0.05). For ΔWID, there was no difference between the studied groups. CONCLUSIONS: Violet LED associated with low concentration bleaching agents did not show a negative effect on dental enamel regarding the surface microhardness. All bleaching protocols were effective, therefore, perceptible to human eyes.

Bleaching sensitivity with a desensitizing in-office bleaching gel: a randomized double-blind clinical trial.

OBJECTIVES: This split-mouth study assessed the bleaching sensitivity (risk and intensity) and color change after in-office bleaching using a desensitizing-containing (5% potassium nitrate) and a desensitizing-free 35% hydrogen peroxide gel. The null hypothesis was that there would be no differences between study groups regarding bleaching sensitivity. METHOD AND MATERIALS: Sixty patients participated in this split-mouth study. The subjects received desensitizing-containing hydrogen peroxide in half of the maxillary arch, and the other half received a desensitizing-free hydrogen peroxide, defined by random sequence, in two dental bleaching sessions. The bleaching sensitivity was evaluated during bleaching and from 1 h to 48 h after each bleaching session using a visual analog scale and numeric rating scale; the McNemar test, the Wilcoxon signed-rank test, and the Student-Newman-Keuls test were used for statistical analysis. The color was measured at baseline and 30 days post-bleaching, evaluated with paired t tests (P = .05). RESULTS: Statistically similar risks of bleaching sensitivity were observed (P = 1.000), but the intensity of bleaching sensitivity was lower (P < .011) on average by 1.32 visual analog scale units in the group bleached with the desensitizer-containing gel during up to 24 h assessment times. No statistical difference in color change was observed between groups (P > .321). CONCLUSION: The incorporation of 5% potassium nitrate into in-office bleaching gels does not reduce the risk of bleaching sensitivity, but it reduces its intensity slightly without jeopardizing color change.