The effect of different parameters of low-level laser used in the treatment of oral mucositis, on the viability and apoptosis of oral squamous cell carcinoma cells: In vitro study.

Oral mucositis is a complication of chemo/radiotherapy. To assess the impact of various power levels of diode-laser on the survival and expression of apoptosis-related genes in oral cancer cells, it is crucial to consider the potential existence of malignant cells within the treatment region and the reliance of laser effectiveness on its specific characteristics. Cal-27 cells were cultivated and exposed to a 660 nm-diode-laser at power levels of 20, 40, and 80 mW, alongside non-irradiated control cells. Viability and expression of Bax and Bcl-2 mRNA were assessed with Methyl Thiazolyl Tetrazolium (MTT) and Real-time Polymerase Chain Reaction (RT-PCR), respectively. The results were analyzed using one-way ANOVA and Tukey post-hoc test (p < 0.05). A significant reduction in viability was found only in the 20 mW group compared to controls (p = 0.001). Cell survival was significantly lower in cells receiving 20 mW laser than those treated with 40 and 80 mW (p < 0.05). None of the laser groups showed significant changes in BcL-2, but Bax was significantly lower in cells receiving 40 and 80 mW (p < 0.05), compared to controls. Laser irradiation at 660 nm (2 J/cm², 30 s) significantly reduced the viability of oral cancer cells when using 20 mW power. These specifications align with the recommendation that the lowest possible laser dose should be applied for treating cancer patients. The exact mechanism of cell death following laser therapy with these specifications requires further investigation.