The study aimed to compare the effectiveness of an experimental gel that contained 6% hydrogen peroxide, titanium dioxide (TiO2), and chitosan nanoparticles with that of the two bleaching agents that are routinely used and evaluate their effectiveness in a 3-month period. Seventy-two extracted premolar teeth were divided into three groups for the bleaching procedure. TiO(2)and chitosan were added to increase the whitening effect of the low-concentration experimental gel. In group 1, the experimental gel was applied and activated with a D-Light Duo LED device. In group 2, Opalescence Boost PF was applied chemically. In group 3, Philips Zoom was applied and activated with Zoom Advanced Power. The color of the teeth was measured with a Vita Easyshade Advance 4.0 spectrophotometer before the bleaching and 24 hours, 7 days, 14 days, 30 days, and 3 months after final bleaching. The CIEDE2000 color differences ( increment E-00) and averageL*,a*, andb* values were calculated. Effective bleaching was observed in three groups as determined by the initial color at different measurement times (P < .05). Philips Zoom showed a higher value of color change than the other groups at all times. The experimental gel showed a bleaching activity like that of Opalescence Boost PF at all-time measurements. A slight decrease in color change was observed between the first-month measurement and third-month measurement in all groups. A low-concentration experimental gel containing TiO(2)and chitosan provided effective whitening, and the whitened color persisted throughout the 3-month period.