Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 23 0 2026 04 27 4592 4592 Samar Rahimpour Department of Oral and Maxillofacial Medicine, School of Dentistry, Iran University of Medical Sciences, Tehran, Iran Arash Azizi Department of Oral and Maxillofacial Medicine, TeMS.C., Islamic Azad University, Tehran, Iran Mahshid Hodjat Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran Mohammad Vahedi Department of Oral and Maxillofacial Medicine, TeMS.C., Islamic Azad University, Tehran, Iran 2022 09 10 2023 11 14 Objectives: This study evaluated the effects of 660 and 940nm lasers on viability and proliferation of stem cells from human exfoliated deciduous teeth (SHED). Materials and Methods: SHED were cultured and divided into six groups for laser irradiation: 660nm laser at 25mW with energy densities of 1 and 2J/cm2 for 8 and 16 seconds, and 940nm laser at 100mW with the same energy densities and durations. Two additional groups served as controls with no laser exposure. Cell viability was evaluated by the methyl thiazolyl tetrazolium (MTT) assay, and cell proliferation was measured by cell counting with a Neubauer chamber and qualitatively evaluated by 4′,6-diamidino-2-phenylindole (DAPI) staining at 24 and 72 hours post- irradiation. Data were analyzed using one-way ANOVA, followed by Tamhane’s and Tukey’s tests. Results: Irradiation with 940nm laser enhanced cell proliferation compared to both 660nm laser and control groups at 24 and 72 hours (P<0.05), as confirmed by DAPI staining. At 24 hours, all laser-treated groups showed increased cell viability relative to the control, although the increase in the 660nm/2J/cm² group was not statistically significant (P>0.05). At 72 hours, only 940nm laser group showed significantly higher cell viability and proliferation than the control group (P<0.05). Conclusion: These findings suggest low-level laser therapy, particularly at the wavelength of 940nm enhances the viability and proliferation of stem cell, supporting its potential as a promising tool in regenerative medicine and tissue engineering. https://fid.tums.ac.ir/index.php/fid/article/view/4592 https://fid.tums.ac.ir/index.php/fid/article/download/4592/2207