Investigating the Effect of Photobiomodulation Therapy With Different Wavelengths of Diode Lasers on the Proliferation and Adhesion of Human Gingival Fibroblast Cells to a Collagen Membrane: An In Vitro Study

<b>Introduction:</b> Photobiomodulation (PBM) is considered a promising adjunctive approach in regenerative medicine. This study aimed to investigate the proliferation and adhesion of human gingival fibroblast (HGF) cells to a collagen membrane following PBM. <b>Methods:</b> Cultured HGF cells on a collagen membrane received PBM at wavelengths of 808 nm, 915 nm (2 and 4 J/cm²), and 660 nm (2.1 and 4.2 J/cm²) in interventional groups, while non-irradiated cells served as the control. On days 1 and 3 post-irradiation, cell proliferation was measured by MTT assay, and adhesion to the membrane was assessed under the scanning electron microscope (SEM). <b>Results:</b> Cell proliferation significantly increased in interventional groups compared to the control, with the most significant increase at 915 nm (4 J/cm²) in both time points. On the first day, the 808 nm and 660 nm lasers demonstrated similar results, significantly lower than the 915 nm laser (2 J/cm²). On day 3, the 660 nm, 808 nm, and 915 nm (2 J/cm²) groups showed comparable results. Qualitative analysis by the SEM identified spindle-shaped cells with multiple extended projections in 915 nm groups, especially at an energy density of 4 J/cm². Groups of 660 nm and 808 nm (4 J/cm²) showed spindle-shaped cell morphology. No distinct cellular morphology indicative of enhanced adhesion was observed at 808 nm (2 J/cm²). <b>Conclusion:</b> The most effective PBM setup for promoting HGF proliferation and adhesion to a collagen membrane was identified at 915 nm (4 J/cm²).