630 nm light-emitting diode irradiation suppresses inflammation and promotes osteoblast differentiation in periodontal cell models - in vitro study.

BACKGROUND

Periodontal disease involves persistent inflammation and alveolar bone loss. Photobiomodulation using light-emitting diodes (LEDs) may regulate inflammation and bone remodelling, but the optimal wavelength and irradiation timing remain unclear.

METHODS

Human gingival fibroblasts and RAW 264.7 macrophages were irradiated with 525, 630, or 850 nm LED light before or after lipopolysaccharide (LPS) stimulation. The effects of 630 nm irradiation were further evaluated in primary mouse calvarial osteoblasts, MC3T3-E1 cells, bone marrow-derived macrophages, and RAW 264.7 osteoclast precursors. Inflammatory mediators, nitric oxide production, cell viability, osteoblast differentiation, and osteoclast formation were assessed.

RESULTS

Among the wavelengths tested, 630 nm irradiation most consistently reduced pro-inflammatory cytokine expression and secretion and decreased nitric oxide production without affecting cell viability. In primary osteoblasts and MC3T3-E1 cells, 630 nm irradiation at 5 and 10 J/cm² increased alkaline phosphatase (ALP) activity, osteogenic marker expression, RUNX2 protein levels, and Smad1/5/9 phosphorylation. In contrast, the same irradiation conditions did not significantly affect osteoclast differentiation or the expression of osteoclast-related markers.

CONCLUSION

Irradiation with 630 nm LED light suppressed inflammatory responses and promoted osteoblast differentiation without enhancing osteoclastogenesis. These findings suggest that 630 nm photobiomodulation may provide a balanced therapeutic approach for periodontal disease, although further validation in animal models and clinical studies is required.