Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 16 6 2020 06 24 458 464 EN Reza Saeedi Department of Operative Dentistry, School of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Ladan Ranjbar Omrani Laser Research Center of Dentistry, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran Mahdi Abbasi Laser Research Center of Dentistry, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran Nasim Chiniforush Laser Research Center of Dentistry, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran Mojgan Kargar Department of Pediatric Dentistry, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran 2019 05 19 2019 07 19 Objectives: Light irradiation and heat have been used to accelerate the process of tooth bleaching. This study aimed to assess the efficacy of conventional bleaching compared to laser-bleaching using three different wavelengths of diode lasers. Materials and Methods: In this in-vitro experimental study, 40 extracted human central incisors were immersed in a coloring solution made of tea, coffee, and cola for 21 days. The L*, a*, and b* color parameters were measured before and after the immersion using spectrophotometry. The teeth were then randomly divided into four groups (n=10) as follows: group 1: 810-nm diode laser + Biolase Laser White 20, group 2: 940-nm diode laser + Biolase Laser White 20, group 3: 980-nm diode laser + Biolase Laser White 20, and group 4: conventional bleaching with Opalescence Boost without laser irradiation. One-way analysis of variance (ANOVA) was used to assess the effect of laser type and bleaching technique on color parameters. Results: The 940-nm (∆E=28.5896) and 810-nm laser groups (∆E=21.2382) showed the highest and the lowest bleaching efficacy, respectively; however, the groups were not significantly different in terms of bleaching efficacy (P>0.05). Conclusion: Laser-bleaching with 810-, 940- and 980-nm wavelengths of diode laser has an efficacy similar to that of conventional bleaching but in a shorter period. No difference was noted between different laser wavelengths in terms of bleaching efficacy. https://fid.tums.ac.ir/index.php/fid/article/view/3150 https://fid.tums.ac.ir/index.php/fid/article/download/3150/1789