Laser photobiomodulation does not alter clinical and histological characteristics of 4-NQO-induced oral carcinomas and leukoplakia in mice.

Abstract

This study evaluated the effect of laser photobiomodulation (PBM) on oral leukoplakia and squamous cell carcinomas (OSCC) in a model of oral carcinogenesis. Forty-one C57Bl/6 female mice were distributed in control group, 4-NQO group, Laser group 1.5J and Laser group 9J. Oral cancer was induced on the tongue by nitroquinoline oxide (4-NQO), diluted in the water for 16weeks. In the 18th and 19th weeks, PBM with a diode laser, 0.028cm2 spot size, continuous emission mode, 660nm wavelength was applied on the tongue of animals for seven sessions. Laser group 1.5J received 30mW power and 1.5J energy. In the Laser group 9J, 100mW power, and 9J energy were applied. In the 20th week the animals were euthanized. All animals exposed to carcinogen developed clinical and histological alterations such as leukoplakia and OSCC on the tongue. There was no significant difference among Laser groups 1.5 and 9J and 4-NQO group (not irradiated) regarding the area of leukoplakia and carcinomas (P >0.05) or thickness of epithelial tissue and keratin (P>0.05). There were also no association between PBM and histologic classification of the lesions (P =0.87), frequency of OSCC (P =0.57), grade of tumor differentiation (P =0.88) or depth of invasion (P =0.45). Laser PBM, in both parameters used, does not influence on clinical and histological characteristics of oral leukoplakia and OSCC. Results suggest that PBM may be a safe treatment for adverse effects of antineoplastic therapies in patients with leukoplakia and OSCC.