Effects of low intensity laser irradiation during healing of skin lesions in the rat

Objective To determine whether laser light can improve healing of skin wounds by killing wound bacteria while simultaneously accelerating host tissue activity. Materials and Methods Wounds on the rat dorsum were irradiated or sham-irradiated three times weekly from days 1 to 19 using 635 or 808 nm diode lasers at 1 or 20 J/cm2. Wound area and bacterial growth were evaluated three times weekly. Histological analysis was performed on days 8 and 19. Immunohistochemical analysis was performed on day 19. Results Wounds that were irradiated using 635 nm light at 1 J/cm2 healed similarly to controls. Wounds that were irradiated using 808 nm (1 and 20 J/cm2, P≤0.05) and 635 nm light (20 J/cm2, P≤0.05) were worse in wound maximum area at day 3 compared with controls. Further, 635 nm light at 20 J/cm2 delayed wound closure at day 19 (ASL = 0.0127). Bacterial colonization of wounds was altered using 635 nm (20 J/cm2, P