In Vitro Photobiomodulation Effects of Blue and Red Diode Lasers on Proliferation and Differentiation of Periodontal Ligament Mesenchymal Stem Cells.

Introduction: This study aimed to assess the photobiomodulation effects of blue and red lasers on the proliferation and osteogenic differentiation of periodontal ligament mesenchymal stem cells (PDLMSCs). Methods: PDLMSCs were cultured and tested in 4 groups. The first two groups were exposed to 445 nm diode laser irradiation (200 mW, 6 and 12 J/cm 2 ), and the third group was exposed to 660 nm diode laser irradiation (50 mW, 4 J/cm 2 ). The fourth group was also considered as the control group without irradiation. Cell viability/proliferation was assessed by MTT assay. RUNX2, alkaline phosphatase (ALP), collagen type 1 (col1), and osteocalcin (OCN) were evaluated by RT-PCR, and Alizarin red was used to evaluate the colonization. The data were analyzed by means of one-way analysis of variance. Results: The results of our study showed that cell survival/proliferation in the second group was significantly lower than that in the control group on days 1 and 7 ( P <0.05). RT-PCR showed a significant increase in osteogenic genes in all three laser groups compared to the control group ( P <0.05). All groups showed a significant increase in calcium content compared to the control group ( P <0.05). ALP activity also confirmed the osteoblastic differentiation of cells in laser groups. Conclusion: 445 nm and 660 nm lasers with the studied parameters showed positive effects on the proliferation and osteoblastic differentiation of PDLMSCs.