Effectiveness and safety of biosilicate-enhanced bleaching gels on enamel with early erosion lesion

This study evaluated the efficacy and cytotoxicity of 35% hydrogen peroxide (HP) gel incorporated with 10% (w/w) biosilicate (BioS) on sound enamel and early-stage enamel erosion lesions.

Discs of enamel/dentin were selected, subjected to erosive cycles (0.3% citric acid, pH 2.6), and treated with (n = 8): HP (35% HP, positive control); HP_BioS [carboxymethyl cellulose (CMC) + HP + BioS]; BioS (CMC + BioS); CMC (negative control). The discs were adapted to artificial pulp chambers with the enamel exposed for bleaching, and the dentin facing toward the culture medium (Dulbecco's modified Eagle's medium [DMEM]). Bleaching was performed in three 30-min sessions at 7-day intervals. After bleaching, the diffusion product (DMEM extract + diffused HP) was pipetted onto MDPC-23 odontoblastic cell line and inoculated. Color parameters (ΔL, Δa, Δb), color change (ΔE₀₀), and changes in whiteness index (ΔWI_D) were determined before (T₀) and after the last bleaching session (T₃). Cell viability (MTT, %), H₂O₂ diffusion (μg/mL), oxidative cell stress (OxS), and cell fluorescence (live/dead assay, in confocal microscopy) were assessed (ANOVA/Tukey; α = 0.05).

No difference in ΔL, Δa, Δb, ΔE₀₀, and ΔWI_D were found between HP and HP_BioS (p > 0.05). The incorporation of BioS decreased the HP diffusion into the substrates and mitigated oxidative stress in early-stage eroded enamel (p < 0.05). HP_BioS presented significantly higher cell viability compared with HP under erosion conditions. Live/dead assay indicated that BioS_HP maintained viability with larger clusters of viable cells.

Incorporating BioS into HP maintained bleaching effectiveness, favored cell viability, reduced the oxidative stress, and the cytotoxicity in teeth with early-stage erosion.

BioS formulation showed promising results for reducing cytotoxicity in patients seeking tooth bleaching and presenting undetectable early-stage erosion.