Effect of Low-Level Laser Therapy with Output Power of 30 mW and 60 mW in the Viability of a Random Skin Flap

Abstract

To assess the effects of low-level laser therapy (LLLT) with output power of 30 and 60 mW in the viability of a random skin flap in rats. Output power values in LLLT are not well defined. Controlled, single-blind experimental study. Thirty-six animals were randomly distributed into three groups: sham group (SG), 30-mW output power (30G), and 60-mW output power (60G). In both treated groups, a fluency of 3 J/cm(2) was used. Two minutes after elevation of a random-pattern cranially based dorsal flap (4 x 10 cm), laser irradiation was applied and repeated on the first, second, third, and fourth postoperative days. Percentages of flap necrosis were calculated on the seventh postoperative day. Also, four fragments of each flap were collected to allow determination of the percentages of vascular density according to the bidimensional method of the morphometric analysis of blood vessels. Statistical analysis included the Wilcoxon test and Kruskal-Wallis variance analysis. A significance level of 5% was elected (p < 0.05). Laser-treated animals presented significantly less necrosis than the sham group (SG, 53%; 30G, 24%; p < 0.05) (60G, 25%; p < 0.05). Also, laser-treated animals presented significantly more vascular density than the sham group (SG, 37%; 30G, 57%; p < 0.05) (60G, 59%; p < 0.05). LLLT (660 nm) with 30-mW and 60-mW output power was efficient in the increase of skin flap viability, but there was no difference between them.