Red, infrared, and simultaneous laser-wavelengths irradiation effects on 5-fluorouracil-induced oral mucositis in hamsters

The association of more than one wavelength for photobiomodulation therapy (PBMT) to treat oral mucositis (OM) is unusual in the literature. Thus, this study aims to compare the simultaneous irradiation effects with their isolated application to treat OM. In order of that, 48 male Syrian hamsters were divided into 4 groups: Chemotherapy (Ch), which received only a OM induction protocol (5-fluorouracil chemotherapy and superficial oral mucosa scratches); red laser (RL), which received the OM induction and a PBMT protocol at 660 nm; infrared laser (IRL), which received the OM induction, and a PBMT protocol at 808 nm; and the RL + IRL group, which received the simultaneous application, of 660 and 808 nm wavelengths. Clinical (OM grade classification), histological (light microscopy analysis with H & E and collagen staining), immunohistochemical (TNF-a expression), and biochemical (TNF-a and hydroxyproline concentration) analyzes were performed after 7 and 10 days. Mainly on the 10th day, the RL and IRL groups showed lower OM grades and faster microscopic repair process, with greater expression of collagen fibers and lower TNF-a levels, besides the higher hydroxyproline concentrations, mainly in comparison with the Ch group. In conclusion, in this study, the simultaneous protocol did not present superior results than the isolated irradiations.