Fluence-Dependent Effects of 940-nm Photobiomodulation on the Proliferation and Osteoblastic Differentiation of Human Periodontal Ligament Stem Cells

Background/Objectives: Photobiomodulation (PBM) has been proposed to regulate periodontal tissue remodeling, but its effects on osteoblastogenesis in periodontal ligament stem cells (PDLSCs) remain highly dependent on laser parameters. This study investigated the fluence-dependent effects of 940 nm diode laser irradiation on the proliferation and osteoblastic differentiation of human PDLSCs.

Methods

Six primary human PDLSC cultures were established and characterized using flow cytometry and multilineage differentiation assays. Cell proliferation was assessed after a single irradiation at fluences of 1, 2, 4, and 10 J/cm2. Osteoblastogenesis was induced using repeated irradiation regimens initiated at 2, 4, or 10 J/cm2 under suboptimal or complete osteogenic conditions and evaluated by Alizarin Red staining on day 21. The expression of osteogenic genes (RUNX2, BMP2, SPP1, TGFB1, COL1A1, ALPL, and BGLAP) was evaluated by qRT-PCR at different time points. Culture supernatants were analyzed for soluble osteogenic mediators.