Effects of 660 nm and 810 nm Low‐Power Diode Laser on Proliferation and Invasion of Oral Cancer Cells in Cell Culture Media

In the present study, the effects of 660 and 810 nm diode laser on the proliferation and invasion of cancer cells were investigated. Sixteen plates of oral cancer cells originated from tongue SCC were irradiated with diode laser at 660 nm (40 and 80 mW) and 810 nm (100 and 200 mW) with the energy density of 4 J cm−2. One plate received no irradiation (the control). Irradiation was performed at four times (0, 24, 72 and 168 h). Cell proliferation was measured by MTT assay. The Ki67 and vascular endothelial growth factor (VEGF) markers were examined by real‐time polymerase chain reaction (RT‐PCR). Cyclin D1, E‐cadherin, β‐catenin and matrix metalloproteinase‐9 (MMP‐9; flow cytometry) were also evaluated. Proliferation was lower in the irradiated groups. This result was significant for all groups at 24 h. The percentages of cyclin D1 and MMP‐9 were higher in 810 nm groups, β‐catenin and E‐cadherin were higher in 660 nm groups, VEGF marker was significantly lower in 810 nm/200 mW group, and Ki67 marker has no difference between the groups. According to the results of this study, laser irradiation at 0 and 24 h resulted in a significant inhibitory effect on cell proliferation especially in 660 nm/80 mW and 810 nm/200 mW. Further studies are needed in this respect. It seems that lower wavelengths (660 nm) performed more safely, and at each wavelength, the higher powers (80 mW and 200 mW) were more desirable on the proliferation and invasion of oral cancer cells. Time was also an important factor in the effectiveness of the laser on cancer cell proliferation, and two times laser irradiation (0 and 24 h) resulted in a significant inhibitory effect.