effect of low level laser therapy on wound healing

ABSTRACT

The present study was performed to evaluate the effects of low level laser therapy [LLLT] on wound healing and to compare between the effects of two types of laser on this process. Forty-five albino rats [200-250 gm body weight] were used and divided into three equal groups [A; B; C,]. 2x2 cm skin flaps were removed at the back, on both sides, under ketamine Hcl-anaesthesia, in all rats. Post-wounding, the animals of groups A, B were irradiated by Helium-Neon [He-Ne] and Diode Laser, every other day, for twenty days, respectively. The animals of group C were not irradiated and served as controls. On the 3[rd], 10[th] and 20[th] days after irradiation, five rats from each group were sacrificed. The skin defects were excised, fixed in 10% neutral formalin and processed to obtain 6mm thick paraffin sections stained with Hx and E and Mallory stains. The percentage of wound closure was calculated using the MATLAB 6 computer program. Furthermore, histological evaluation and scoring was preformed regarding epithelialtzation, cellular infiltration, granulation tissue formation, collagen deposition and vascularity. The data were statistically analysed for the test of significance, compared to the control values. On the 3[rd] day post-wounding, the control wounds were covered by dirty crusts under which there were heavy cellular infiltration, vascular congestion and few collagen bundles. After He-Ne Laser, there were markedly dilated capillaries, cellular infiltration and an excess amount of collagen fibers. After Diode Laser irradiation, markedly dilated, congested capillaries, cellular infiltration and regularly arranged collagen fibers were encountered, under the crust. After 10 days, there were dilated, congested capillaries, moderate cellular infiltration and irregularly arranged collagen bundles, in the control, non-irradiated wounds. After He-Ne Laser, the granulation tissue contained proliferating, congested blood capillaries, scattered fibroblasts and more or less regularly arranged collagen bundles. After Diode Laser, the granulation tissue lodged numerous dilated, congested capillaries, mild cellular infiltration, and regularly arranged collagen bundles with intervening fibroblasts. Significant wound closure and histological scoring were recorded in laser irradiated groups, compared to the control one, and in the Diode treated group, compared to He-Ne treated one. Twenty-days post-wounding, the skin wounds healed by scars formed of coarse irregularly oriented collagen bundles, covered by irregular epithelial surfaces, in the control group. After He-Ne. there was complete healing with more or less regularly oriented collagen bundles and regular superficial epithelium. However, Diode Laser resulted in a complete healing process with well-combed collagen bundles and regular, healthy coveting epithelium. Highly significant measurement were recorded in laser treated groups compared to the control one. In addition comparison between those after Diode Laser were highly significant, compared to He-Ne data. It could be concluded that laser irradiation could enhance wound healing without deformed scars. It could be also emphasized that Diode Laser was more effective than He-Ne in this respect