Objective: To evaluate, using histological analysis, the systemic action and repair process of wounds produced on the back of rats and treated with red, infrared, or both lasers applied directly or indirectly to the wounds. Background Data: Skin tissue repair and wound healing are complex processes that involve a series of dynamic events. Many benefits are associated with biomodulation uisng laser therapy. Methods: Thirty-six male Wistar rats were divided into four groups: control (without laser), red laser (aluminium gallium indium phosphide (AlGaInP); λ = 685 nm; λ = 0.0314 cm Three wounds were produced on the back of each animal. Only the wound closest to the head was irradiated in the experimental groups. For the evaluation of skin reaction and wound healing, three animals of each group were killed at 3, 5, and 7 days postoperatively. The irradiation protocol established 48-hour intervals between applications, with the first application immediately after the surgical procedure. Results: In the red and infrared laser group, healing was more advanced in the wound located furthest from the point of laser application. The most effective healing of a proximal wound was verified in the control group on the 7th postoperative day. Conclusion: The combined application of red and infrared lasers resulted in the most evident systemic effect on the repair of skin wounds produced in rats.

This study evaluated the use of red and infrared lasers on tissue surrounding the femurs of 60 rats randomly divided into three groups after implantation of bioabsorbable plates. The control group were not subjected to laser irradiation; group A was treated with red laser [indium-gallium-aluminum-phosphide (InGaAlP) laser, wavelength 685 nm, 35 mW, continuous wave (CW), Ø = 0.06 cm, 2.23 min], and group B was subjected to infrared laser [gallium-aluminum-arsenium (GaAlAs) laser, wavelength 830 nm, 50 mw, CW, Ø = 0.06 cm, 1.41 min], both at 10 J/cm(2). Samples were stained with hematoxylin and eosin (H&E) and examined microscopically. Results showed that the laser irradiation had had a positive photobiomodulation effect on inflammation, confirmed by a better histologic pattern than that of the control group at 3 days and 7 days. Semiquantitative analysis revealed that groups A and B had a histologic score significantly greater than that of the control group at 3 days. At 21 days, histomorphometric analysis revealed a more intense inflammation in the red laser group than in the other groups. We concluded that low-level laser therapy (LLLT) has positive effects on the photobiomodulation of inflammation in the tissues surrounding the poly-L-lactic/polyglycolic acid (PLLA/PGA) bioabsorbable plate. It stimulated vascularization, fibroblast proliferation, and collagen deposition.