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Revista do Colégio Brasileiro de Cirurgiões

Print version ISSN 0100-6991On-line version ISSN 1809-4546

Rev. Col. Bras. Cir. vol.41 no.2 Rio de Janeiro Mar./Apr. 2014

http://dx.doi.org/10.1590/S0100-69912014000200010 

Review

Effects of low-level laser therapy on wound healing

Fabiana do Socorro da Silva Dias Andrade 1  

Rosana Maria de Oliveira Clark 2  

Manoel Luiz Ferreira 2  

2.Veterinary Medicine, State University of Santa Cruz, Ilheus, Bahia State - BA, Brazil

ABSTRACT

OBJECTIVE:

To gather and clarify the actual effects of low-level laser therapy on wound healing and its most effective ways of application in human and veterinary medicine.

METHODS:

We searched original articles published in journals between the years 2000 and 2011, in Spanish, English, French and Portuguese languages, belonging to the following databases: Lilacs, Medline, PubMed and Bireme; Tey should contain the methodological description of the experimental design and parameters used.

RESULTS:

doses ranging from 3 to 6 J/cm2 appear to be more effective and doses 10 above J/cm2 are associated with deleterious effects. The wavelengths ranging from 632.8 to 1000 nm remain as those that provide more satisfactory results in the wound healing process.

CONCLUSION:

Low-level laser can be safely applied to accelerate the resolution of cutaneous wounds, although this fact is closely related to the election of parameters such as dose, time of exposure and wavelength.

Key words: Skin; Wound healing; Anti-inflammatory agents; Laser therapy, low-level

INTRODUCTION

The incorporation of laser as a therapeutic tool has been accompanied in the biomedical field since 1960 by Theodore Maiman. One of the first published experiments on the effects of low-level laser dates from 1983, with HeNe (Helium Neon) laser irradiation of wounds in rats for 14 consecutive days1.

The effects of low-level laser can be observed in the behavior of lymphocytes, increasing their proliferation and activation; on macrophages, increasing phagocytosis; and on fibroblasts, increasing the secretion of growth factors and enhancing the uptake of both fibrin as collagen. In addition, it contributes to increase the motility of epithelial cells, the amount of granulation tissue and may reduce the synthesis of inflammatory mediators2 - 5. Its action can be observed on the reduction of the area of skin wounds in humans and animals, although the adoption of physical variables involved in the treatments is still not a consensus among authors6 - 9.

Regarding the irradiation protocol, the use of lasers may differ in the type of activation means, the power and dose, and also on the manner and time of irradiation and number of applications3.

From the above, and with the growing interest in alternatives to conventional drug therapies, the objective of this was to gather and clarify the actual effects of low-level laser therapy on wound healing and its most effective ways of application in human and veterinary medicine.

METHODS

This was a qualitative study from original articles published in journals indexed in the following databases: Lilacs, Medline, PubMed and Bireme. We included all original articles whose publication occurred between the years 1984 and 2011 in Spanish, French, English and Portuguese languages and provided methodology containing the parameters used by the applied laser mode. We excluded the research articles that did not contain the methodology regarding the description of the parameters used in their work.

LITERATURE REVIEW

The acronym LASER has its origin in the English language, abbreviating "light amplification by stimulated emission of radiation". The word laser is established by usage and defines a source of monochromatic, intense, coherent and collimated light, whose emission of radiation is done by stimulating the external field, with varied and growing applications in industry, engineering, human medicine and more recently, veterinary medicine10 , 11. In the latter, the rat has been used to study the different aspects involved in cutaneous healing process, being the elected experimental model due to ease of handling12.

Lasers are classified into high and low power. The first is generally applied for the removal, cutting and coagulating of tissues, while the low-power ones are more commonly applied in the processes of tissue repair, such as muscle, joint, nerve, bone and skin injuries6 , 13 , 14.

The photobiological effects of laser radiation can be conventionally divided into short and long term. The responses in the short term are those in which the effect can be observed in a few seconds or minutes after irradiation. The effects observed in the long term are those that occur hours or even days after the end of irradiation and usually involve new cell biosynthesis, especially in the proliferative phase of inflammation12 , 15 , 16.

A wide variety of lasers that promote wound healing can be found in the literature, including:. Helium-Cadmium, Argon, Helium-Neon, Krypton, Gallium Arsenide and Aluminium and CO2 6. It is known, however, that the success of low power therapy and its respective effects is dependent on wavelength, power, dose and time of application4 - 8 , 11 , 16 - 23 (Table 1).

Tabela 1 Breve descrição das propostas de tratamento com laserterapia de baixa potência e seus principais resultados. 

Authors Treatment Resiults
Busnardo, Simões, 20108 HeNe with power 4J/cm2 applied for 12 seconds per wound
site in continuous mode, 5mW, wavelength of 632.8 nm and
the laser beam area of 0.015 cm2.
Increase of type III collagen, decreased
inflammatory infiltrate and early resolution
of wound inflammatory phase.
Silva et al., 201016 Laser applied in 15 Wistar rats divided into three groups: G1
(control), G2 (2J/cm2) and G3 (4 J/cm2), with wavelength of 670
nm and irradiated for 10 consecutive days on skin lesion.
The dose of 4J/cm2 differed significantly
from the others concerning the reepithelialization
process.
Frigo et al., 200917 Application of laser once a day on tumor cells, for three
consecutive days, with the following parameters: 632nm, 50
mW, 2mm2 pointer, irradiation area of 2.5 W/cm2 and times of
60 and 420 seconds at doses of 150J/cm2(group 1, in vitro) and
1050J/cm2 (group 2, in vivo), respectively. The third group was
not irradiated (control group).
Between the in vitro and the control group,
there was no statistically significant
difference in the growth of tumor cells.
Comparing group 2 and control, there was
significant growth of mass and volume to
the tumor, as well as a large number of
blood vessels in the in vivogroup.
Felice et al., 20097 Application of AlGaInP laser (658 nm, 4J/cm2) in a localized and
scanned manner on human decubitus and venous ulcers.
Reduction of the wounds area.
Maiya et al., 200918 He-Ne laser on skin wounds in diabetic rats, with a wavelength
of 632.8 nm and doses of 3-9J/cm2, five days / week until
complete healing.
Increased production of granulation tissue
in the animals that received doses of 4-5J/
cm2, especially on the fifth day of
treatment.
Inoe et al., 200811 HeNe laser used in doses of 3 and 6J/cm2, 45 W of power and
wavelength of 632nm and a control group, for surgical wounds
of healthy rabbits. The animals were evaluated at 7, 14 and 21
days.
Observed the presence of mature
granulation tissue at 14 days and absence
of hemorrhage and exudate at day 21.
Channual et al., 20085 Low power laser with a wavelength of 585 nm and a dose of
7J/cm2 on skin wounds of rats.
Permanent vascular proliferation after the
fifth day of application.
Pinto et al., 20074 First week twice with an interval of 48 hours in the weeks
following 1x/week, in a localized manner and without the use
of additional medication.
The results revealed granulation tissue,
reducing inflammation and pain relief from
the first application.
Castano et al., 200719 Arthritis in rats treated for five days with 810nm, power 79
and 790mW, doses of 3 and 30J/cm2 and intensities of 5 and
50mW/cm2.
Increase of adenosine triphosphate (ATP)
and improved inflammatory process.
Rocha Júnior et al., 200620 Twelve animals divided into two groups: control and experimental.
Wound treated for seven days with GaAs laser, pulsatile
dose 3.8 J/cm2 and power of 15mW time for 15 seconds.
Tissue repair significantly larger and more
organized in the experimental group.
Hopkins et al., 200421 Abrasive damage induced in non-dominant upper limb in two
groups of healthy people. One group was treated with a dose
of 8J/cm2, wavelength 820nm and two minutes exposure. The
other group was treated under the same parameters for five
seconds. A third group was not treated.
The groups treated with low level laser
showed a statistically significant reduction
in the wound when compared to the
control group at the 6th, 8th and 10th days
of treatment.
Envemeka, 200122 HeNe laser (632.8 nm, continuous) and GaAs laser (904nm,
continuous) in cutaneous lesions of rats.
Improvement of wound healing for both
wave lengths adopted, though the latter
presented more pronounced findings.
Landau, Schattner, 200123 HeNe laser (632nm / 5mW and 904 nm/60W; 4 J/cm2) associated
with topical hyperbaric oxygen supply for 20 minutes per session
on diabetic foot ulcers over 14 weeks.
Complete healing of ulcers after 25 sessions
and only 4% of recurrence.
Al-watban, Andres, 20016 HeNe (632.8 nm wavelength, dose of 5 J/cm2 and power of
10.53 mW/cm2), applied three times per week in in vivo cells
until complete healing of the wound.
Increased cell proliferation (fibroblasts and
mitochondria), as well as microcirculation, with
a consequent increase in cellular metabolism.

DISCUSSION

The repair process is complex and comprises vascular and cellular alterations, epithelial and fibroblasts proliferation, synthesis and deposition of collagen, elastin and proteoglycan production, revascularization and wound contraction8. Noteworthy still are the trophic-regenerative, anti-inflammatory and analgesic effects2 , 8 , 24. It is also claimed that the low-level laser therapy can lead to increased mitochondrial activity, with a consequent increase of adenosine triphosphate (ATP), vasodilation, protein synthesis, decrease in prostaglandin levels, presence of cellular mitosis, migration and proliferation of keratinocytes and neoangiogenesis18 , 19 , 23 , 25.

In this sense, a study with HeNe laser, applied at the rate of 4J/cm2 showed better effects in the production of collagen type III. In another, it was observed that doses between 7 and 9 J/cm2 caused the opposite effect, reducing the production of collagen fibers2 , 18.

It is understood that the increased collagen production occurs through photostimulation mechanisms on which certain frequencies/doses may act, thereby modulating cellular proliferation and increasing the amount of fibroblast growth factors. Another possible explanation for this, according to the authors above, would be the better absorption of such energy by the mitochondria and consequently increased production of ATP and nucleic acid, the result being an increase in collagen production, accelerated epithelial repair and facilitated growth of granulation tissue26.

According to Zanotti et al.9, excitatory doses (up to 8J/cm2) are indicated when the goal of the intervention includes the enhancement of the sodium/potassium pump; stimulating production of ATP; restoration of the membrane potential; increased metabolism and cell proliferation.

Laser therapy has been administered with the aim of promoting better resolution of inflammation, reducing pain, preventing the occurrence of edema and preserving tissues and nerves adjacent to the site of injury. Such effects can be achieved via wavelengths between 600 and 1000nm and power from 1mW to 5 W/cm2. The authors also emphasize that very low (2.5W/cm2) or very high (25 W/cm2) power can cause the opposite effect27.

In a study treating the inflammatory process present in induced arthritis of the knee joint of rats with anti-inflammatory and low-level laser therapy, beneficial effects have been observed both at a dose of 3J/cm2 and 30J/cm2, although the latter proved more effective in reducing the painful area over 120 hours after the start of treatment, when associated with lower power and applied for ten minutes19. Bashardoust Tajali et al.3 reported that the wavelength of 632nm improved resolution of fractures, thereby demonstrating that there are many results for the use of this therapy.

Although laser has been successfully applied on the symptoms of various diseases, investigators showed that malignant melanoma cells irradiated by Indium-Gallium-Aluminum-Arsenic-Phosphorus (InGaAlAsP) laser at 660nm wavelength and dose of 1050J/cm2 revealed worsening behavior17. Furthermore, the use of laser is contraindicated in cases of localized or irradiated malignant tumor; epilepsy; on the thyroid gland; on pregnant abdomen; high hypersensitivity; and thrombosis of pelvic or deep leg veins28 , 29.

FINAL CONSIDERATIONS

It is concluded that low-level laser therapy, when applied to skin wounds, is able to promote major physiological effects, such as anti-inflammatory resolution, neoangiogenesis, epithelial and fibroblasts proliferation, collagen synthesis and deposition, revascularization and wound contraction. It is also possible to say that doses of 3-6 J/cm2 appear to be more effective and doses above 10 J/cm2 are associated with deleterious effects. The wavelengths between 632.8 and 1000 nm remain as those having more satisfactory results in the wound healing process.

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How to cite this article: Andrade FSSD, Clark RMO, Ferreira ML. Effects of low-level laser therapy on wound healing. Rev Col Bras Cir. [periódico na Internet] 2014;41(2). Disponível em URL: http://www.scielo.br/rcbc

Received: October 10, 2012; Accepted: December 15, 2012

Address for correspondence: Fabiana do Socorro da Silva Dias Andrade E-mail: fabi4000@gmail.com

Conflict of interest: none.

Source of funding: none.

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