Abstract: Abstract: Objective Tooth color is one of the most important concerns for orthodontic patients in pursuing facial aesthetics. The purpose of this study was to evaluate the effect of clear overlay retainers on the color of teeth. Methods Control group: 30 healthy volunteers. Treatment group: 30 patients treated with clear overlay retainers. According to the system of the Commission Internationale de l’Eclairage (lightness, red/green, and yellow/blue)，we measured the color of anterior teeth and premolars of subjects using a spectrophotometer at 0 and 12 months. Results The treatment group included 408 teeth, and control group included 408 teeth. L* decreased, a*, b* increased in the two groups. ΔE control group = 0.80±0.35, ΔE treatment group = 1.53±0.65; In the treatment group, ΔE前牙=1.67±0.67，ΔE前磨牙=1.22±0.47，P<0.01. No effect was found of gender on the color of teeth (P> 0.05). Conclusion Natural tooth has a tendency to darken, turn yellow and turn red; the tooth color of the treatment group changes more.

Key words: orthodontics, clear overlay retainers, tooth color