Whitening Efficacy and Enamel Protection of 35% Hydrogen Peroxide Solution Containing Alkaline-Substituted Bioactive Glasses

High Resolution Image Download MS PowerPoint Slide This study aimed to investigate the whitening efficacy and enamel surface protective effects of 35% hydrogen peroxide (HP) solutions modified with alkali-substituted bioactive glasses (BAGs). Three alkali BAG formulations (K-, Li-, and LiK-based) were added to 35% HP at concentrations of 0.1, 1.0, and 10.0 wt %. The control group contained HP without BAG or distilled water (DW). The pH of each solution was monitored. Discolored bovine enamel specimens were treated thrice with each solution (20 min/session). Enamel surface color change (Δ E ) was assessed by spectrophotometry, while surface gloss, roughness (Ra), and Vickers microhardness were also measured. Morphological alterations were examined by scanning electron microscopy (SEM). Statistical analysis was performed using one-way analysis of variance with Tukey’s post hoc test (α = 0.05). All BAG-modified groups showed significantly higher pH values than HP alone ( p < 0.05), with K- and LiK-based formulations producing the greatest pH increases. Except for Li 0.1%, the Δ E values of all formulations were statistically comparable to those of HP ( p > 0.05), indicating no loss of whitening efficacy. BAG addition significantly improved gloss and microhardness and reduced roughness compared with HP alone ( p < 0.05). At concentrations ≥ 1%, enamel surface properties were restored to levels similar to those of DW ( p > 0.05). SEM revealed progressively smoother enamel surfaces with increasing BAG concentration. In conclusion, incorporating alkali-substituted BAGs into 35% HP preserved bleaching efficacy while markedly reducing enamel surface damage; concentrations ≥ 1% showed the most consistent protective effects. High-concentration HP bleaching may compromise enamel integrity despite its whitening effectiveness. The addition of alkali-substituted BAGs effectively buffered the bleaching environment and promoted surface protection without impairing whitening efficacy. This approach represents a promising adjunct for safer and more predictable in-office bleaching procedures.