This study aimed to evaluate the bleaching efficacy and hydrogen peroxide permeability in the pulp chamber by the at-home bleaching gel in protocols applied on different dental surfaces.

Forty premolars were randomly into 4 groups: control group no bleaching, only application on the buccal surface (OB), only application on the lingual surface (OL) and application in buccal and lingual surfaces, simultaneously (BL). At-home bleaching gel (White Class 7.5%) was used for the procedure. The bleaching efficacy was evaluated with a digital spectrophotometer (color change in CIELAB [ΔE _ab] and CIEDE 2000 [ΔE ₀₀] systems and Whitening Index for Dentistry [ΔWI_D]). The hydrogen peroxide permeability in the pulp chamber (µg/mL) was assessed using UV-Vis spectrophotometry and data were analyzed for a 1-way analysis of variance and Tukey’s test (α = 0.05).

All groups submitted to bleaching procedure showed bleaching efficacy when measured with ΔE _ab and ΔE ₀₀ (p > 0.05). Therefore, when analyzed by ΔWI_D, a higher bleaching efficacy were observed for the application on the groups OB and BL (p = 0.00003). Similar hydrogen peroxide permeability was found in the pulp chambers of the teeth undergoing different protocols (p > 0.05).

The application of bleaching gel exclusively on the OB is sufficient to achieve bleaching efficacy, when compared to BL. Although the OL protocol demonstrated lower bleaching efficacy based on the ΔWI_D values, it may still be of interest and relevant in certain clinical scenarios based on individual needs, requiring clinical trials to better understand its specificities.