Effects of visible or IR Laser light on the progression of chemo-induced oral dysplasia: In vivo study on the hamster cheek pouch model

摘要

Oral Epithelial dysplasia may be a white, red or mixed patch that may affect several sites of the mouth. Chemo-induced precancerous lesions are standard model to study cancer on the oral cavity. The use of Laser photobiomodulation on the oral care is a standard procedure these days and it is known that it proliferative effects on both cells and tissues depending on dose, wavelengths and other parameters. The aim of this study was to assess the effect of laser light on the evolution of chemo-induced epithelial dysplasia on the hamster cheek pouch model. Sixteen animals were divided into four groups: Control (n=8), Laser λ660nm (n=4), and Laser λ790nm (n=4). DMBA induction was carried out three times a week. All animals presented epithelial dysplasia seven days after first induction. When appropriate, laser (λ660nm or λ790nm, 30/40mW, φ ～ 3mm, 4J/cm~2) was used at 48 h interval during two weeks. Chemo-induction continued during all experimental period (6 weeks). Following animal death, specimens were taken, routinely process to wax, cut and stained with H.E. Slides were analyzed under light microscopy by an oral pathologist using WHO (2005) criteria for epithelial dysplasia. At the end of the experiment, 100% of control specimens snowed mild epithelial dysplasia. On laser irradiated animals, 75% of the specimens showed mild epithelial dysplasia and 25% showed moderate ones extending beyond the medium third of the epithelium. It was concluded that the use of both wavelength and a dose of 4J/cm~2 may increase the severity of oral epithelial dysplasia.