Evaluation of the Effects of Photobiomodulation of Low-Level Laser on Total Thickness Burn Induced in Animal Model

Abstract

Aim study was to evaluate the effects of low-power laser photobiomodulation (LBP) in third-degree burns induced in an animal model. Forty Wistar rats (Ratus norvegicus albinus) were used, females weighing between 200 and 300 grams, randomly divided into a control group (GC = 20) and a laser-treated group (DL = 20). A 1cm² third-degree burn injury was performed on the back of each animal after trichotomy and followed by surgical debridement 24 hours after induction. In the treated group (LBP) a laser was applied at a wavelength of 660 nm, a power of 27 mW and an average irradiance of 0.954 W / cm2 at five points of the wound. The total fluency was 350 Joules / cm2 and application of 5 Joules per wound. Biopsy fragments were collected on days 3, 7, 15 and 21 post-injury for macro and microscopic analysis using the techniques of Hematoxylin and Eosin (HE), Gomori's Trichrome (TG) and Picrosirius red. The results were evaluated by Tukey's Test and Analysis of Variance (ANOVA), Kruskal-Wallis Test (non-parametric) and T-paired Test. The healing process evaluated by morphometry showed a relative statistical difference between the CG and LBP groups. Histopathological analysis showed a decrease in the inflammatory infiltrate, angiogenesis, synthesis of granulation tissue and collagen deposition, increased fibroblasts, matrix organization, and reepithelization of the lesion. Thus, low-power laser photobiomodulation can contribute to the wound repair process efficiently.