The Effect of Low Reactive-Level Laser Therapy (LLLT) with Helium-Neon Laser on Operative Wound Healing in a Rat Model

Abstract

ABSTRACT. The effect of low reactive-level laser therapy (LLLT) with a He-Ne laser on operative wound healing was investigated in a rat model. 10-millimeter surgical wounds were created on the backs of Sprague Dawley rats, and animals were assigned to one of eleven groups (n=5). Ten groups received either 8.5 mW or 17.0 mW irradiation of 15 seconds LLLT a day with one of five different irradiation frequencies, i.e. daily (from the 1st to 6th day following surgery), every other day (the 1st, 3rd, and 5th day), on only the 1st day, on only the 3rd day, and on only the 5th day; the 1st day was the day following the surgery. The control group received no irradiation. A skin specimen was harvested from the dorsal thoracic region on the 7th day to measure the rupture strength. The control group had the lowest rupture strength (5.01 N), and the 17.0 mW every other day irradiation group had the highest rupture strength (13.01 N). Statistical differences were demonstrated in the 8.5 mW irradiation setting between the every other day irradiation group and the control group (p<0.05); and in 17.0 mW irradiation setting between the every day irradiation, the every other day, and the 1st day only groups vs. the control group (p<0.01). Histological examination demonstrated that wound healing in the 17.0 mW every other day irradiation group was promoted most significantly such as the prevention of excessive inflammation, increased formation of collagen fibers, and recovery in continuity of tissues. The control group showed poor wound healing and the other experimental groups showed intermediate healing.Thus LLLT with a He-Ne laser was found to promote the healing of operative wounds in the present rat model, in which the most favorable application of LLLT was the 17.0 mW setting of 15 seconds a day with a frequency of every other day. KEY WORDS: He-Ne laser, LLLT, low reactive-level laser therapy, wound healing.J. Vet. Med. Sci. 69(8): 799-806, 2007 Low reactive level laser therapy (LLLT) [26] has been utilized clinically since the first successful cases reported by Mester [21][22][23]. Many studies have been published and various effects of LLLT have been reported such as (1) promotion of wound healing [3, 5, 14-19, 28, 29, 31-33], (2) alleviation of pain [4,7,32], (3) improvement in local circulation [20], and (4) alleviation of inflammation [2,7,8], and (5) bactericidal effects [12].In spite of this various fundamental questions have not yet been answered. Regarding wound healing, for example, it is not certain when LLLT should be performed following injury, or what level and frequency of irradiation is effective [35,36]. There are also reports that deny any effect of LLLT on wound healing [9,28], and doubts about its effect on neurological functions have also been voiced [7]. One of the reasons why such controversy arose may be the lack of an evaluating method to enable us to examine the effects of LLLT with sufficient accuracy.Focusing attention on the promotion of wound healing by LLLT, and on the fact that the functio...

A efetividade do laser de HeNe 632,8 nm no reestabelecimento da integridade dos tecidos cutâneos em animais experimentais: revisão sistemática

“…No estudo de Busnardo et al 15 , foram incluídos 60 de tais animais, os quais, após a recuperação anestésica, foram devidamente marcados e distribuídos aleatoriamente em dois grupos, Controle e Experimental, compostos por 30 animais cada. Por fim, o estudo de Yasukawa et al 16 , que incluiu 55 animais divididos em 11 grupos, sendo 1 Controle e 10 Experimentais (Tabela 2).…”

“…Os autores iniciaram a terapia com laser 24 horas após a realização da lesão, porém não foram unânimes em relação aos parâmetros empregados, à frequência de Yasukawa et al 16 (Japão) 2007 X X X 3 1: declaração de controle de temperatura; 2: cegamento para indução da lesão; 3: cegamento para avaliação do desfecho; 4: modelo animal apropriado; 5: cálculo de amostra; 6: concordância com regulamentos de bem-estar animal; 7: declaração de potenciais conflitos de interesse; 8: randomização aplicação do laser, assim como ao tempo para a realização da análise histológica (Tabela 2). Araújo et al 13 , em seu estudo, utilizaram uma potência contínua (PC) de 10 mW e densidade de energia (DE) de 1 J/cm 2 durante três minutos (tempo calculado de acordo com a área) para o Grupo Experimental (GE).…”

“…Os animais foram submetidos à eutanásia em cada um dos tempos e foram ressecados segmentos de pele da cicatriz para análise. Yasukawa et al 16 realizaram um estudo, em que os dez subgrupos do GE receberam PC de 8,5 ou 17 mW e DE de 2,09 ou 4,21 J/cm 2 , respectivamente, por 15 segundos de laser HeNe. As frequências de aplicação foram realizadas em cinco períodos distintos: diariamente (primeiro ao sexto DPO); de forma intercalada (primeiro, terceiro e quinto DPO); apenas no primeiro; apenas no terceiro e apenas no quinto DPO.…”

“…No entanto, esta não foi possível devido à impossibilidade de comparação entre as metodologias dos estudos inclusos. 13,15,16 incluíram ratos Wistar adultos submetidos à indução anestésica para realização de tricotomia da região dorsal, seguida de antissepsia local e incisão longitudinal no dorso, com espessura compreendida entre a pele e a tela subcutânea. Araújo et al 13 realizaram duas incisões com 6 mm de diâmetro cada.…”

“…No estudo de Busnardo et al 15 , realizou-se apenas uma incisão com aproximadamente 4 cm, nela foram aplicados quatro pontos separados por 1 cm de distância entre eles. Yasukawua et al 16 realizaram 3 incisões de 15 mm cada.…”