Whitening toothpastes with hydrogen peroxide concentrations vs. at-home bleaching

To evaluate the effect of whitening toothpastes with different hydrogen peroxide (HP) concentrations on HP permeability, color change, and physicochemical properties, compared to at-home bleaching treatment.

Forty-nine premolars were randomized into seven groups (n = 7): untreated (control); at-home bleaching with 10% carbamide peroxide gel (AH; 10% CP) with 14 and 28 applications of 180 min each (AH [14 × 180 min] and AH [28 × 180 min]); three whitening toothpastes (3% HP; 4% HP and 5% HP) and 10% CP brushed 28 times for 90 s each (TB [28 × 90 s]). HP permeability was measured using a UV-VIS spectrophotometer and color change by a digital spectrophotometer (ΔE_ab, ΔE₀₀, and ΔWI_D). Initial concentration, pH, and viscosity were measured through titration, digital pH meter, and rheometer, respectively. Statistical analysis included one-way ANOVA, Tukey's test, and Dunnett's test (α = 0.05).

4% HP group showed acidic pH, the lowest viscosity and the highest HP concentration into the pulp chamber (p < 0.05). The 10% CP groups had lower HP in the pulp chamber and greater color change than other groups (p < 0.05), except the 5% HP group in ΔE_ab and ΔE₀₀. For ΔWI_D, the 10% CP AH groups showed greater whitening than other groups (p < 0.05).

Whitening toothpaste with up to 5% HP resulted in higher HP permeability and less color change compared to 10% CP. Higher HP commercial concentrations in toothpaste increased whitening effect; however, acidic pH toothpastes exhibited greater HP permeability.

Whitening toothpastes with high hydrogen peroxide concentrations were less effective than at-home bleaching, resulting in less color change and greater permeability of hydrogen peroxide, potentially increasing the risk of tooth sensitivity.