Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 19 0 2022 12 21 3847 3847 Fatemeh Ebrahimzadeh Private Practice, Kashan, Iran Hooman Fakhar Department of Restorative Dentistry, Faculty of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Hossein Akbari Department of Biostatistics and Epidemiology, Faculty of Health and Hygiene, Kashan University of Medical Sciences, Kashan, Isfahan, Iran Ramin Mosharraf Department of Prosthodontics, Dental Materials Research Center, Dental Sciences Research Center, Faculty of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran Azin Farzad Department of Restorative Dentistry, Faculty of Dentistry, Kashan University of Medical Sciences, Kashan,Isfahan, Iran 2020 11 15 2021 07 07 Objectives: This study compared the effect of two whitening toothpastes on composite specimens discolored with 0.2% chlorhexidine (CHX). Materials and Methods: Twenty-four composite specimens were fabricated from Charisma Diamond composite resin. The initial color of specimens was measured according to the CIE L*a*b* color system using a spectrophotometer. The specimens were immersed in 0.2% CHX twice a day for 1 minute each time, for 2 weeks. The color of specimens was measured again, and the specimens were assigned to three groups (n=8). The control group specimens were immersed in distilled water. The two test group specimens were brushed twice daily for 21 days with Oral B toothbrush and Signal White Now and Crest 3D White whitening toothpastes each time for 30 seconds. The color of specimens was measured again. Data were analyzed by one-way ANOVA and t-test. Results: CHX increased the a, b, and L color parameters in all groups.  There were no significant differences in ΔL (P=0.10), Δa (P=0.24), and Δb (P=0.07) among the study groups. The a, b, and L parameters decreased after brushing the specimens discolored with 0.2% CHX with the whitening toothpastes. There were significant differences in ΔL (P=0.03), Δa (P=0.02), and Δb (P=0.01) among the three study groups after using the whitening toothpastes. The highest ΔL, Δa, Δb, and ΔE values were recorded in Crest 3D White group, followed by Signal White Now group. Conclusion: Crest 3D White whitening toothpaste had higher efficacy to resume the original color of composite specimens discolored with 0.2% CHX. https://fid.tums.ac.ir/index.php/fid/article/view/3847