Comparative assessment of bleaching of natural teeth using ozone-enhanced low-concentration hydrogen peroxide

To compare the efficacy of using a low concentration of hydrogen peroxide (HP) followed by ozone (7%-15% HP and ozone) and using a high concentration of HP (35% HP) in bleaching of natural teeth. In addition, the bleaching efficacy of ozone alone was evaluated in comparison to 7%-35% HP and ozone.

This randomized controlled in vitro study was carried out on 75 extracted human teeth with intact enamel. The teeth were randomly allocated to 5 groups (15 teeth per group) and were then bleached with either ozone alone, 35% HP and ozone, 15% HP and ozone, 10% HP and ozone, or 7% HP and ozone. Teeth shades (including CIELab values) were measured at baseline and after bleaching using conventional (VITA classic and 3D Master shade guides) and digital (Easyshade and Rayplicker Handy spectrophotometers) methods. Data were analyzed using ANOVA, repeated measures ANOVA, and Bonferroni post hoc tests (α = 0.05).

The mean ΔE₀₀ was larger than 1.8-2.00 threshold values in all groups, indicating perceived and identified bleaching effects by human eye. Groups 1 (ozone only) and 5 (7% HP + ozone) were associated with less Δshade between baseline and ozone bleaching than Groups 2 (35% HP + ozone), 3 (15% HP + ozone), and 4 (10% HP + ozone) (p ≤ 0.001). Without using ozone, bleaching with 35% HP resulted in superior bleaching effects (higher ΔE₀₀ values) when compared with 7% and 15% HP (p < 0.05). However, when followed by ozone, bleaching using lower concentrations of HP (7%-15% HP) resulted in similar bleaching outcomes (similar ΔE₀₀ values) when compared with bleaching using 35% HP (p > 0.05). Bleaching using ozone alone resulted in weaker bleaching effects when compared with HP with ozone (p < 0.05).

Incorporating ozone into HP-based bleaching protocols would significantly enhance whitening efficacy. This combination enables the use of lower HP concentrations (7%-15% HP) without compromising bleaching results. This confirms ozone's value as a supportive bleaching agent that might have the potential to improve patient safety and comfort. Although bleaching with ozone alone yielded perceived color changes, it yielded inferior bleaching effects compared to bleaching using HP followed by ozone.