In Vitro Effects of 915 Nm and 635 Nm Diode Lasers on Osteogenic Differentiation of Human Pdl Mesenchymal Stem Cells Publisher



Fathi Vajargah P ; Karimi M ; Hodjat M ; Etemadi A ; Saberi S
Source: Lasers in Dental Science Published:2026

Abstract

Purpose: This study aimed to evaluate the effects of 635 nm and 915 nm diode lasers—each at a fixed energy density of 4 J/cm²—on the proliferation and osteogenic differentiation of human periodontal ligament mesenchymal stem cells (PDLMSCs). Methods: In this in vitro experimental study, human PDLMSCs cultured in osteogenic medium were irradiated with 635–915 nm diode lasers at 4 J/cm² energy density. Cell proliferation was assessed using the MTT assay at 24, 48, and 72 h. Alkaline phosphatase (ALP) activity was measured at day 7. Calcium deposition was evaluated on day 14 using Alizarin red staining and CPC calcium quantification. Osteogenic gene expression (Col1, OCN, and OSN) was analyzed using real-time PCR. Results: Both 635 nm and 915 nm laser irradiation significantly increased PDLMSC proliferation at 48 and 72 h, with the 915 nm group showing higher levels (P < 0.001). ALP activity and calcium content were significantly elevated in both laser groups compared to control (P < 0.01), with the 915 nm laser inducing a greater effect. Alizarin red and CPC analysis confirmed significantly enhanced mineralization in laser-irradiated groups (P < 0.0001). Gene expression of Col1, OCN, and OSN was significantly upregulated in both laser groups, particularly in the 915 nm group (P < 0.0001). Conclusion: Laser irradiation at both 635 nm and 915 nm wavelengths with 4 J/cm² energy density promotes proliferation and osteogenic differentiation of human PDLMSCs. These findings suggest the potential application of diode lasers, particularly at 915 nm, for regenerative periodontal therapies. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2026.