Objective: The aim of this study was to assess the bleaching efficacy and impact on psychosocial and esthetics self-perception of a low-concentration (6%) hydrogen peroxide (H2O2) gel compared with a conventional (37.5%) H2O2 gel when used as an in-office treatment. Method and Materials: In total, 35 participants received two sessions of three 12-minute applications of treatment with 37.5% H2O2 on one side of the mouth and 6% H2O2 on the other. Color changes were measured objectively using total variation in color (ΔE) and subjectively using Vita Classical scale (ΔSGU). The Psychosocial Impact of Dental Aesthetic Questionnaire (PIDAQ) and Oral Health Impact Profile (OHIP-14) esthetic questionnaires were administered to measure self-perception and the psychosocial impact of the whitening procedure. Results: Both gels produced significant changes in tooth color at 1 and 3 months post-whitening. The objective efficacy (ΔE) of 37.5% H2O2 (9.06 ± 2.96) was significantly higher than that of 6% H2O2 (5.69 ± 3.06). The results of the subjective assessment were not statistically different. There was a positive impact on esthetic auto perception (OHIP-14, P .05) and psychosocial impact (PIDAQ, P .05) at the 3-month time point. Conclusion: Low concentration of H2O2 (6%) achieved effective bleaching (ΔE > 5 units) with good stability at 3 months accompanied by a positive psychosocial impact and enhanced self-perception. However, the traditional 35% concentration was objectively more effective. Keywords: low concentration, OHIP, PIDAQ, quality of life, tooth bleaching