Background and Objective. Despite the fact that the molecular mechanism of low-level laser therapy (LLLT) is not yet known, the exploitation of phototherapy in clinical medicine and surgery is of great interest. The present study investigates the effects of LLLT on open skin wound healing in normal and diabetic rats. Materials and Methods. Four round full-thickness skin wounds on dorsum were performed in male adult nondiabetic (n = 24) and diabetic (n = 24) Sprague–Dawley rats. AlGaInP (635 nm, wavelength; 5 J/cm2, daily dose) was used to deliver power densities of 1, 5, and 15 mW/cm2 three times daily until euthanasia. Results. PMNL infiltration was lower in the irradiated groups (15 mW/cm2). The synthesis and organisation of collagen fibres were consecutively enhanced in the 5 mW/cm2 and 15 mW/cm2 groups compared to the others in nondiabetic rats. In the diabetic group the only significant difference was recorded in the ratio PMNL/Ma at 15 mW/cm2. A significant difference in the number of newly formed capillaries in the irradiated group (5, 15 mW/cm2) was recorded on day six after injury compared to the control group. Conclusion. LLLT confers a protective effect against excessive inflammatory tissue response; it stimulates neovascularization and the early formation of collagen fibres.

The optimal parameters for low-level laser therapy (LLLT) for wound healing are still open to discussion. Hence, our study was aimed at comparing the effects of different power densities of LLLT at 670 nm in rats. Four round full-thickness skin wounds were placed on the backs of 16 rats which were divided into two groups (non-steroid and steroid-treated). Three wounds were stimulated daily with a diode laser (daily dose 5 J/cm(2)) at different power densities (5, 15 and 40 mW/cm(2), respectively), and the fourth wound served as a control. Six days after surgery all animals were killed and samples removed for histological evaluation. Significant acceleration of fibroblast proliferation and new vessel formation was observed in wounds treated at the selected power densities. No significant differences were found in corticosteroid-treated rats. In conclusion, LLLT with the methodology used improved wound healing in non-steroid rats, but was not effective after corticosteroid-treatment.