Effects of low-level laser therapy under different protocols on skin wound healing in rats

Abstract

Although there are many studies confirming laser biomodulation, appropriate parameters and treatment protocols have not yet been established. The aim of this study was to analyze the effects of a low-level laser therapy under different protocols on skin wound healing in rats. Standardized 8-mm circular wounds were made in the dorsal midline backs of forty rats. The animals were divided into four groups: G1, without laser; G2, laser immediately after surgery; G3, laser immediately after surgery and again after 48 h; G4, laser immediately after surgery, after 48 h and after seven days. The wound areas were measured immediately after surgery, after 48 h, after seven days and after ten days (when the animals were sacrificed) using an image analysis software. After sacrifice, the wounds and surrounding tissues were removed and submitted to routine laboratorial processing and histological slide confection. Six slides of each animal were photographed, and fibroblast counts were made. For statistical evaluation, the Kruskal-Wallis test and a 5% significance level were used. The control group showed less progression of repair than other groups at all observation times, highlighting the effect of lasers in healing in biometrical analysis. Irradiated groups showed increased fibroblast proliferation relative to the control group, and the protocol with two periods of irradiation resulted in higher fibroblast numbers after ten days. It was concluded that the laser treatment aided in wound healing and that the repair process was faster in the groups that received more than one application of the laser.