Effects of Violet and IR LED Light on mast cell degranulation: in vivo study in a murine model

The aim of this study was to evaluate the influence of IR (λ850 ± 10 nm) and violet (λ405 ± 10 nm) LED phototherapy on total mast cells counts and its ability to influence mast cell degranulation. For this, 27 Wistar rats were used and were randomly distributed into three groups: control, IR LED, and violet LED. When indicated, irradiation done and they were sacrificed, had their tongue removed immediately, 20-min, 45-min, and 2-h after irradiation. Samples were processed to wax, cut, and stained with Toluidine Blue. Intact and degranulated mast cells were counted under light microscopy, and statistical analysis was carried out. In the superficial connective tissue and muscular tissues, violet LED light caused a significant increase in both total number and degranulated mast cells when compared to the control group immediately after irradiation. The degranulation indexes were higher in the groups irradiated with Violet light, both in superficial connective tissue and muscular tissues in relation to the timing. Irradiation with IR LED caused immediate increase in the total number and degranulated of mast cells when compared to the control group only in the superficial connective tissue. In all times observed, the highest total amount of mast cells was seen immediately after irradiation, except in the muscular tissue, which presented the highest amount after 20-min. It was concluded that IR and violet LED light were able to increase the number of mast cells and inducing degranulation in oral mucosa. However, considering that violet LED light can be harmful in periodontal disease, it seems that the use of IR LED light could be the best option in Dentistry.