Objectives: To evaluate the effect of hydroxyapatite nanoparticles' addition and determine the utility role of CO2 laser in improving esthetics of enamel surfaces after debonding. Methods: 90 extracted human premolars were used. 10 teeth were used as a control group. Trans bond Plus Self Etching Primer with Trans bond Supreme Low Viscosity Light Cure Adhesive, 3M/Unitek, was used to bond the orthodontic brackets (NU-EDGE.022" ROTH RX.TP Orthodontics) to the labial enamel surfaces. All specimens were stored in artificial saliva for 6 months. Orthodontic brackets were then removed using bracket removing pliers (Ortho Organizers, Carlsbad, USA).Residual composite removed by Sof-Lex finishing discs. The 80 teeth were divided randomly into 4 groups (n=20) according to the protocol of nanoparticles' addition, 1) no nanoparticles were added, 2) nanoparticles suspended in water and rubbed on the dry enamel surface, 3) nanoparticles suspended in ethanol and rubbed on the etched enamel surface, and 4) nanoparticles suspended in bonding agent [Single Bond 2 adhesive (SB)] & rubbed on the etched enamel surface. Each group assigned into two subgroups (n=10) according to exposure to CO2 laser (9.6μm), where enamel of the first subgroup was irradiated at 3W; 20Hz; 4sec and 212J/cm2 while the other subgroup was not irradiated. The SE bonding agent was applied to the third group after its treatment. Specimens were tested for color changes using Quanta Environmental Scanning Electron Microscope. Data were statistically analyzed using two-way Analysis of Variance (ANOVA) and Tukey's post-hoc test. Results: highest mean color value was found with no particles. There was no significant difference between group 1 and 2. There was no difference between groups 3 and 4; both showed the statistically significant lowest mean color values. Meanwhile, no significant effect was found between laser and non-laser subgroups. Conclusions: the addition of hydroxyapatite nanoparticles improved the enamel esthetics after brackets debonding.