Influence of laser (λ670 nm) and dexamethasone on the chronology of cutaneous repair.

OBJECTIVE: This study aimed to assess the effect of LLLT associated with and without dexamethasone on inflammation and wound healing in cutaneous surgical wounds. BACKGROUND: Limited studies are directed at the possible interference of laser photobiomodulation on the formation of myofibroblasts, associated with an antiinflammatory drug. METHODS AND MATERIALS: Standard skin wounds were performed on 80 Wistar rats, distributed into four groups: no treatment (sham group), laser only (λ670 nm, 9 mW, 0.031 W/cm(2), 4 J/cm(2), single dose after surgery), dexamethasone only (2 mg/kg 1 h before surgery), and laser with dexamethasone. Tissue was examined histologically to evaluate edema, presence of polymorphonuclear, mononuclear cells, and collagen. The analysis of myofibroblasts was assessed by immunohistochemistry and transmission electron microscopy. The intensity was rated semiquantitatively. RESULTS: The results showed that laser and dexamethasone acted in a similar pattern to reduce acute inflammation. Collagen synthesis and myofibroblasts were more intense in the laser group (p = 0.048), whereas animals treated with dexamethasone showed lower results for these variables. In a combination of therapies, the synthesis of collagen and actin and desmin-positive cells was less than laser group. CONCLUSIONS: Laser was effective in reducing swelling and polymorphonuclear cells and accelerated tissue repair, even in the presence of dexamethasone.

Effect of 670-nm laser therapy and dexamethasone on tissue repair: a histological and ultrastructural study.

OBJECTIVE: In this study we investigated the role of extracellular matrix elements and cells during the wound healing phases following the use of low-level laser therapy (LLLT) and anti-inflammatory drugs. BACKGROUND DATA: There are few scientific studies that characterize the possible interactions of LLLT and anti-inflammatory medications. MATERIALS AND METHODS: Thirty-two rats submitted to a wound inflicted with a 6-mm-diameter punch. The animals were divided into four groups: sham treated, those treated with the GaAlAs laser (4 J/cm(2), 9 mW, lambda = 670 nm, spot size 28.27 x 10(2) cm(2)), those treated with dexamethasone (2 mg/kg), and those treated with both LLLT and dexamethasone. After 3 and 5 d, the cutaneous wounds were assessed by histopathology using polarized light and ultrastructural assessment using transmission electron microscopy. Changes seen in polymorphonuclear inflammatory cells, edema, mononuclear cells, and collagen fiber deposition were semi-quantitatively evaluated. RESULTS: The laser-treated group demonstrated increased collagen content and better arrangement of the extracellular matrix (p < 0.05). Fibroblasts in these tissues were increased in number and were more synthetically active. In the dexamethasone group, the collagen was shown to be non-homogenous and disorganized, with a scarcity of fibroblasts. In the group treated with both types of therapy, fibroblasts were more common and they exhibited vigorous rough endoplasmic reticulum, but they had less collagen production compared to those seen in the laser group. CONCLUSION: LLLT alone accelerates post-surgical tissue repair and reduces edema and the polymorphonuclear infiltrate even in the presence of dexamethasone.