A Comparative Study of the Effects of Laser Photobiomodulation on the Healing of Third-Degree Burns: A Histological Study in Rats

Abstract

The aim of this investigation was to compare by light microscopy the effects of laser photobiomodulation at wavelengths of 660 and 780 nm on third-degree burns in Wistar rats. Burns are severe injuries that result in the loss of fluid and destruction of tissue, infection, and shock that may result in death. Laser energy has been suggested as an effective method to improve wound healing. Fifty-five animals were used in this study. A third-degree burn measuring 1.5 x 1.5 cm was created on the dorsum of each animal. The animals were divided into three subgroups according the type of laser photobiomodulation they received (wavelength of 660 or 780 nm, 35 mW, theta = 2 mm, and 20 J/cm2). In the animals receiving treatment, it was begun immediately post-burn at four points around the burn (5 J/cm2) and repeated at 24-h intervals for 21 d. The animals were humanely killed after 3, 5, 7, 14, and 21 d by an intraperitoneal overdose of general anesthetic. The specimens were routinely cut and stained, and then were analyzed by light microscopy. The results showed more deposition of collagen fibers, larger amounts of granulation tissue, less edema, a more vigorous inflammatory reaction, and increased revascularization on all laser-treated animals. These features were more evident at early stages when the 660-nm laser was used, and were more evident throughout the experimental period for the animals receiving 780-nm laser therapy. We concluded that laser photobiomodulation using both wavelengths improved healing of third-degree burns on Wistar rats.