Influence of laser phototherapy (λ660 nm) on the outcome of oral chemical carcinogenesis on the hamster cheek pouch model: histological study.

PURPOSE: This study aimed to evaluate, histologically, the effect of low-level laser therapy (LLLT) (λ660 nm) on DMBA chemically induced lesions of the oral mucosa of hamsters. BACKGROUND DATA: Squamous cell carcinoma (SCC) is the most common neoplasm of the oral cavity. It is aggressive, highly proliferative, invasive, and metastatic. There is evidence that LLLT similarly affects neoplasic and non-neoplasic cells. METHODS: Cancerous lesions were induced on the cheek pouch of 15 golden Syrian hamsters by using DMBA 3 times a week for 8 weeks. At the end of the cancer induction (8 weeks), animals in G1 were killed and the presence of tumors confirmed. Animals in G3 were irradiated (λ660 nm, 30 mW, CW, Ø=3 mm, area: 0.07 cm(2), 424 mW/cm(2), 133 sec, 56.4(2)J/ cm(2), 4J) at every other day for 4 weeks. G2 received no interventions for the same period. Samples were taken and underwent histological analysis by light microscopy. RESULTS: GI showed 100% well-differentiated SCC. G2 showed 20% moderately differentiated and 80% well-differentiated SCC. G3 showed 40% well-differentiated, 40% poorly differentiated, and 20% moderately differentiated SCC. Significant differences (p=0.02) in the amount of well-differentiated SCC were seen between G1 and G3 and between G3 and G2 (p=0.04). Significant difference was also seen between G3 and G1 and G2 with regard to the amount of poorly differentiated tumors (p=0.04). CONCLUSIONS: It is concluded that LLLT, within the parameters used in the present study, caused a significant progression of the severity of SCC in the oral cavity of hamsters.

Effect of LED red and IR Photobiomodulation in tongue mast cells in Wistar rats: histological study.

OBJECTIVE: This article aimed to study the effect of LED Phototherapy (LED-PHT) (?630?nm or ?850?nm) on mast cells on the dorsum of the tongue of rodents. BACKGROUND DATA: Vasodilatation is one of the reported effects of laser light on tissues. Laser light is able to induce the release of mediators responsible for vasodilatation, such as those produced by mast cells. Mast cells are also related to some diseases such as hay fever. METHODS: Sixty Wistar rats were divided into three groups: I, Control; II, IR-LED (?850?nm, 21.9?J/cm(2), 73 sec; and III, red-LED (?630?nm, 21.9?J/cm(2), 73?sec). The specimens were taken after, 20, 45, and 60?min following irradiation. The specimens were routinely processed; stained with toluidine blue; and then total, degranulated, and non-degranulated mast cells were counted and statistical analysis performed. RESULTS: Both LED irradiated subjects showed significant difference when compared to the control subjects on the total number mast cells (p<0.001, ANOVA), degranulated mast cells (p<0.001, ANOVA), and non-degranulated mast cells (p<0.001, ANOVA). Comparing the two groups of LED irradiated subjects, significant difference was observed regarding the total number of cells (p<0.001, paired t-test) and degranulated mast cells (p<0.001, paired t-test) with a greater number of these cells noted in the IR-LED group. On the other hand, Red-LED irradiated subjects showed a significantly greater number of non-degranulated mast cells (p=0.001, paired t-test). CONCLUSIONS: Our results lead us to conclude that both red and IR-LED light caused increased mast cell degranulation and that IR-LED light resulted in a greater number of mast cells.