The effects of different doses of 670 nm diode laser on skin flap survival in rats

Abstract

PURPOSE: To investigate the effects of different low-level laser therapy (LLLT) doses on random skin flap rats. METHODS: Forty Wistar rats were randomly divided in four groups. The control group (CG) was not irradiated. The experimental groups were irradiated with a diode laser 670 nm with different energies per point: group 2 (G2) with 0.06 J; group 3 (G3) 0.15 J and group 4 (G4) 0.57 J. The three groups were irradiated in 12 equally distributed points in the cranial skin flap portion. They were submitted to the irradiation during the immediate, first and second postoperative days. The necrosis area was evaluated in the seventh postoperative day. RESULTS: The CG shows 49.35% of necrosis area in the skin flap; G2, 39.14%; G3, 47.01% and G4, 29.17% respectively. There was a significantly difference when G4 was compared with CG`s skin flap necrosis area. CONCLUSION: The low-level laser therapy diode 670 nm with 0.57 J energy per point increases the survival in randomic skin flap rats.

Inhibitory effects of low-level laser therapy on skin-flap survival in a rat model

“…Several authors who used values in this 'therapeutic window' obtained significant increases in tissue viability (5,9,10,12). Doses <0.3 J, as used by Smith et al (3), resulted in no significant alterations in tissue.…”

“…The sample size was calculated considering a difference of 20% in skin-flap necrosis area between the active laser irradiation and sham laser irradiation groups, and an estimated SD of 9.6% based on data from a previous study (9). For a significance level of 0.05 and 80% power, it was estimated that five animals would be required in each group (Minitab version 15, State College, USA).…”

“…The placement of a plastic film was to prevent revascularization from vessels of the underlying tissues, thus ensuring homogeneous conditions of ischemia and necrosis in the animals, as proposed by Korlof and Ugland (18) and revised by Kaufman et al (19). This experimental model has been widely used in previous studies assessing the effects of different treatments to decrease skin-flap necrosis (9,10,12,(21)(22)(23)(24)(25). A suture was performed with simple stitches using 4-0 nylon monofilament, 1 cm from one another ( Figure 3).…”

“…Despite the positive results demonstrated with both types of lasers, some studies suggest that lasers with wavelengths in the red spectrum are more effective at increasing skin flap viability (16). The energy used in previous studies assessing the effects of red lasers in dorsal random skin flaps ranged from 0.06 J to 1.44 J per point (3,9,5,10,12). Energies <0.3 J were ineffective (3,9), whereas energies from 0.3 J to 1.44 J (5,10,12) increased skin flap survival.…”

Princípios fundamentais dos lasers e suas aplicações

“…A fotoquimioterapia é potencialmente segura, aplicável e oferece opções de tratamento para pacientes que sofrem de muitos problemas, se tornando uma outra opção de tratamento às quimioterapias tradicionais. Também não induz resistência aos micro-organismos e não necessita de inúmeras seções de tratamento 12 . Segundo a Sociedade Americana de Câncer, vários fatores são favoráveis ao tratamento com fotoquimioterapia: quando realizada corretamente, não apresenta efeitos colaterais em longo prazo; é menos invasiva que uma cirurgia; normalmente é um procedimento muito rápido e pode ser realizado em ambulatórios; seu alvo de atuação pode ser muito preciso; caso seja necessário, a técnica pode ser repetida várias vezes, ao contrário da radiação; além de apresentar pouca ou nenhuma cicatrização local.…”