Objective: This study investigated whether it is possible to achieve equally satisfactory results between 37.5% hydrogen peroxide (HP) gel and 6% HP gel. We also assessed the psychosocial impact and self-perception of esthetics generated by extracoronal tooth whitening. Methods and Materials: A prospective, double-blind, randomized clinical trial was carried out. A total of 33 patients were selected from the clinic of the Faculty of Dentistry at the University of Chile. The patients included men and women over 18 years old without prior tooth whitening treatments, tooth decay, or restorations of the maxillary anterior teeth. The patients had tooth colors of A3 or less according to the Vita Classical scale, which was determined with a Vita Easy Shade spectrophotometer. The study was carried out with a ‘‘split-mouth’’ design. One side of each mouth was randomly treated with 37.5% HP, and the other side was bleached with 6% HP. Each group received 3 to 12 minutes of