Color change, diffusion of hydrogen peroxide, and enamel morphology after in-office bleaching with violet light or...

The aim is to evaluate the effect of violet light (VL) and nonthermal atmospheric plasma (NTAP) combined with or without 35% hydrogen peroxide (HP) and 37% carbamide peroxide (CP).

Bovine crowns were divided into (n = 10) VL, VL/HP, VL/CP, NTAP, NTAP/HP, NTAP/CP, HP, CP, and C (control) groups. Color and whiteness change (CIELAB-Δ E_ab, CIEDE2000-Δ E₀₀ , whiteness index-ΔWI_D ), color parameters (ΔL, Δa, and Δb), and intrapulpal concentration (μL/mL) of HP were assessed by spectrophotometry. Scanning electron microscopy evaluated the morphology of enamel surface. Data were analyzed by two-way analysis of variance and Tukey (Δ E_ab , ΔE₀₀ , ΔWI_D , ΔL, and μL/mL) and Kruskal-Wallis and Mann-Whitney tests (Δ a and Δ b, α = 5%).

VL increased ΔE_ab and ΔWI_D of CP (P < .05). VL and NTAP alone resulted in perceptible color and whiteness change, but lower than those in the gel-treated groups (P < .05). Activation modes increased ΔL compared with that of C, but only VL enhanced Δb when applied alone or combined with CP. VL and NTAP did not increase HP diffusion (P > .05) or cause alterations in enamel morphology. However, HP and CP promoted topographical changes.

VL and NTAP changed color to a lesser extent than bleaching gels. VL produced supplementary effectiveness only for CP (ΔE_ab and ΔWI_D ), without increasing HP diffusion or changing enamel morphology.

Although violet LED light and nonthermal atmospheric plasma (NTAP) promoted in vitro perceptible bleaching without compromising enamel morphology, bleaching gels (hydrogen peroxide and carbamide peroxide) were more effective than VL or NTAP. VL or NTAP did not increase intrapulpal diffusion of peroxide.