Comparative evaluation to composite resin bleaching using ozone-enhanced low-concentration hydrogen peroxide

To assess the effectiveness of bleaching tea-stained composite resin utilizing low concentration of hydrogen peroxide followed by ozone (7%HP and ozone) compared with high concentration of HP alone (30%HP). Also, to assess the effectiveness of bleaching utilizing ozone alone compared with bleaching utilizing 7% and 30% HP. A controlled randomized laboratory study was conducted on 80 composite discs that were divided into 4 groups. The composite discs were stained with tea solution, and then each group was bleached with ozone alone, 7%HP alone, 7%HP and ozone, or 30%HP alone. The shade of composite discs was recorded at baseline, after staining, and after bleaching. The shade was measured via conventional VITA classic and 3D Master shade guides, Easyshade Spectrophotometer, and Rayplicker Handy spectrophotometer which also measured CIELab shade values. Ozone alone had most inferior bleaching effects on stained composite material among the tested bleaching protocols (P < .05). Shade changes and values were not different between bleaching with 7%HP followed by ozone and bleaching with 30%HP alone (P > .05), except that bleaching with 30%HP alone was associated with higher L* value. Nevertheless, ΔE₀₀ and ΔE_ab were not different between bleaching with 7%HP followed by ozone and bleaching with 30%HP alone (P > .05). Using ozone following 7%HP on stained composite discs yielded similar bleaching outcomes when compared with bleaching using 30%HP alone. Also, ozone alone yielded inferior bleaching effects than bleaching using HP alone or HP followed by ozone.