In recent years, many reports have suggested that photobiomodulation therapy (PBMT) using laser or LED light has wound-healing effects and is effective for early osseointegration of implants. In addition, studies using LEDs often use red LED light with a wavelength of 600-900 nm. On the other hand, there are reports that shorter wavelength light sources, such as green with a wavelength of 500-570 nm, are more effective for cell proliferation. Therefore, we examined the wound-healing effect of PBMT by irradiating rat-derived osteoblast-like cells with green LED light. Osteoblast-like cells collected from rat femurs were cultured and irradiated four times with green LED light at 5.6 J/cm2 for 16 seconds. Comparisons were made between a group irradiated with LED light, a group treated with fibroblast growth factor, a group irradiated with LED light and treated with fibroblast growth factor, and a control group. The wound healing effects were examined by evaluating cell proliferation activity, alkaline phosphatase (ALP) activity, and mineralization ability. LED irradiated cells showed significantly higher cell proliferative capacity than the control group, FGF group and LED + FGF group at 4.5 and 12 hours after irradiation. The ALP activity of the LED irradiated cells was considerably higher than those of the control group, FGF group and LED + FGF group, cells, 5 and 7 days after irradiation. The mineralization ability of LED irradiated cells was higher than those of the control group, FGF group and LED + FGF group 14 days after irradiation. Under the conditions of this study, irradiation of rat osteoblast-like cells with green LED light enhanced cell proliferation, ALP activity, and mineralization. This suggests that green LED light irradiation promotes wound healing.
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