Effect of Brushing With At-Home Bleaching Gel on Hydrogen Peroxide Penetration and Color Change: An In Vitro Study

To evaluate the effect of active at-home bleaching gel application through brushing on hydrogen peroxide (HP) penetration and color change compared to passive application.

Thirty-five premolars were divided into five groups: no treatment; passive application of 10% carbamide peroxide gel (10% CP) 28 times for 180 min (28 AH); and active brushing of 10% CP once (1 TB), 28 times (28 TB), and 120 times for 90 s each (120 TB). Brushing was performed using soft-bristled toothbrushes on stabilized specimens. HP penetration was assessed by UV-VIS spectroscopy, and color change was assessed by spectrophotometer. ANOVA, Tukey's, and Dunnett's tests were used (α = 0.05).

The 120 TB group showed the highest HP penetration (0.022 ± 0.023 μg/mL) (p < 0.05), while the 28 AH (0.009 ± 0.008 μg/mL) and 28 TB groups (0.003 ± 0.003 μg/mL) yielded intermediate, similar results. A similarly high color change was observed in the 28 AH (ΔE _ab = 12.8 ± 1.2; ΔE ₀₀ = 11.2 ± 1.4; ΔWI_D = 22.8 ± 3.2), 28 TB (ΔE _ab = 13.2 ± 4.5; ΔE ₀₀ = 9.5 ± 2.7; ΔWI_D = 16.7 ± 2.0), and 120 TB groups (ΔE _ab = 10.8 ± 1.8; ΔE ₀₀ = 7.5 ± 3.2; ΔWI_D = 19.3 ± 3.4), significantly greater compared to the 1 TB (ΔE _ab = 1.8 ± 0.2; ΔE ₀₀ = 1.2 ± 0.4; ΔWI_D = 1.7 ± 0.7) (p < 0.05).

This in vitro study demonstrates that the active application of 10% CP for 42 min can achieve HP penetration and bleaching efficacy comparable to a passive four-week regimen (28 × 180 min).

This preliminary study suggests that brushing with at-home bleaching gel can achieve a similar hydrogen peroxide penetration into the pulp chamber and color change as traditional at-home bleaching, but in shorter application times.