A Comparative Study of 660 nm Low-Level Laser and Light Emitted Diode in Proliferative Effects of Fibroblast Cells

In recent years the use of low-power lasers has been widely used in medicine. With the introduction of affordable LED light, clinical application of LED light has become more and more popular. However, some researchers believe that because of the lack of coherence of the LED light, it can be different in biological effects in comparison to laser. In this study, we compared the biological effects of low level laser to those of LED light.
Human skin fibroblast cell line Hu02 was irradiated with low level laser and LED light with a wavelength of 660 nm, power output of 35 mW and in continuous mode and the control group was not irradiated. The biological effects were compared through the analyzing of cell proliferation, production of reactive oxygen species within the cell and the rate of cell division.
Our findings showed that production of reactive oxygen species within the cell was linearly increased both in the LED and laser light irradiated cells. However, laser light is more increment in comparison the LED light. The MTT results showed that laser light at low energy density (less than 5 joules per square centimeter) was increased the rate of cell proliferation after 24 hours. Although, the rate of cell division was increased in energy density of 1 J/cm2 compared to the control group, but this increasing was not statistically significant.
The findings indicated that the coherence properties of laser light provided more energy for the cells, and in a constant energy density, laser light created more oxidative stresses in compared with LED light.