Clinical evaluation of in-office bleaching with low, medium, and high concentrate hydrogen peroxide: a 6-month a double-blinded randomized controlled trial

Objective: The study evaluated the longevity, efficacy, sensitivity, and impact on the oral health-related quality of life of in-office dental bleaching using low, medium, and high concentrate hydrogen peroxide. Material and Methods: Randomized, parallel, and double-blinded clinical trial was performed with 54 participants using18% hydrogen peroxide (HP), 25%HP, and 40%HP in-office bleaching agent. Tooth color was evaluated at baseline, after the 1st session bleaching, after the 2nd session bleaching and 6 months after finishing the bleaching using spectrophotometer. Tooth sensitivity (TS) was measured with the Visual Analog Scale at baseline, immediately after bleaching, after 1 day, and after 7 days. The impact on quality of life was evaluated using the 14-item Oral Health Impact Profile (OHIP-14) questionnaire at baseline, and 6 months after bleaching. The data were analyzed using the Kikare test, Kruskal Wallis test, one-way ANOVA, Wilcoxon, Friedman, Mann–Whitney (p < 0.05). Results: All groups achieved similar levels of bleaching during all evaluation times (p > 0.05), surpassing perceived value. There was no difference in TS levels among groups at all evaluation times (p > 0.05). TS significantly increased after bleaching (p < 0.05), decreased significantly after 24 h (p < 0.05), and there was no difference no difference between the initial sensitivity levels after 7 days (p > 0.05). All groups reported improved aesthetic self-perception following bleaching (p < 0.05) and there was no difference between the groups (p > 0.05). Conclusion: Low, medium, and high concentrations of HP did not affect both the final tooth color and the reported TS intensity, regardless of the evaluation time. In-office bleaching provides positive effects on aesthetic perception and different HP concentrations have not influenced this positive effect. Clinical significance: In this study, the efficacy, longevity, sensitivity, and impact on oral health-related quality of life of in-office bleaching using low, medium, and high concentration hydrogen peroxide agents from the same manufacturer were found to be similar. However, these results cannot be extrapolated to other in-office high-concentration hydrogen peroxide gels. Clinical trial registration number: NCT06700434. © The Author(s) 2025.