Abstract
Several studies demonstrate the benefits of low-power light therapy on wound healing. However, the use of LED as a therapeutic resource remains controversial. There are questions regarding the equality or not of biological effects promoted by LED and LASER. One objective of this review was to determine the biological effects that support the use of LED on wound healing. Another objective was to identify LED´s parameters for the treatment of wounds. The biological effects and parameters of LED will be compared to those of LASER. Literature was obtained from online databases such as Medline, PubMed, Science Direct and Scielo. The search was restricted to studies published in English and Portuguese from 1992 to 2012. Sixty-eight studies in vitro and in animals were analyzed. LED and LASER promote similar biological effects, such as decrease of inflammatory cells, increased fibroblast proliferation, stimulation of angiogenesis, granulation tissue formation and increased synthesis of collagen. The irradiation parameters are also similar between LED and LASER. The biological effects are dependent on irradiation parameters, mainly wavelength and dose. This review elucidates the importance of defining parameters for the use of light devices.
INTRODUCTION
A wound is characterized by the interruption on the continuity of a body tissue. It can be caused by any type of physical, chemical and mechanical trauma or triggered by a medical condition.1 Cutaneous wounds are relatively common in adults and their incidence seems to increase in parallel with the advances in life expectancy in the population.2
The therapeutic approach to wound healing consists of preventive measures such as health professional continuing education, family counseling and guidelines to a proper patient nutrition. The use of medicinal plants, administration of essential fatty acids, calcium alginate, antiseptics and degerming products, activated carbon, semi-permeable films, biological collagen, cell growth factors, hydropolymer, hydrogel and hydrocolloid substances, proteolytic enzymes, sulfadiazine silver, gauze dressings, bandages for skin protection and compression are also advocated.3 Physical treatments such as therapeutic ultrasound and electrotherapy are cited likewise in the literature as important adjuncts in wound management.4,5 These therapies seem to be advantageous but they have limitations and do not always achieve satisfactory results.
Wounds that are difficult to heal represent a serious public health problem. The lesions severely affect the quality of life of individuals due to decreased mobility and substantial loss of productivity; they can also cause emotional damage and contribute to increase the burden of public expenditures in healthcare.6
The need to care for a population with poorly healing wounds is a growing challenge that requires innovative strategies. An approach that stands out in the treatment of these lesions is low-power light therapy, promoted by light devices such as LASER (Light Amplification by Stimulated Emission of Radiation) and LED (Light Emitting Diode).
The therapeutic benefits of LASER light in the treatment of wounds have been reported since the 1960s and those of LED light only since the 1990s.7,8 However, many of the results described show inconsistency, mainly due to methodology bias or lack of standardization in the studies. Furthermore, the use of LED as a therapeutic resource remains controversial. There are questions regarding the equality or not of biological and therapeutic effects promoted by LED and LASER resources, but also regarding the appropriate parameters to each of these light sources.
This study aimed to determine, through a literature review: 1 - the biological effects that support the use of light sources such as LED in the treatment of wounds and 2 - the light parameters (wavelength and dose) suitable for the treatment of wounds with LED light sources. The biological effects and light parameters of LED will be compared to those of LASER in order to verify the similarity (or not) regarding wound treatment.
MATERIALS AND METHODS
A literature search was performed in Medline, PubMed, SciELO and Science Direct databases. The literature search was restricted to studies published in English and Portuguese in the period of 1992-2012. The keywords used were "low level laser therapy", "laser", "light emitting diode", "LED", "phototherapy", "wound healing", "fibroblast", "collagen" and "angyogenesis" combined with each other.
RESULTS
Sixty-eight studies were analyzed, including 48 on LASER light, 14 related to LED light and 6 for both types of light (Tables 1 to to3).3). According to data presented on table 1, 16 of the 48 studies on the effects of LASER light were in vitro and 32 were performed in animals.9-56 The use of different wavelengths (532-1064 nm) was verified, with the most utilized spectral range being between 632.8 and 830 nm. Doses ranging from 0.09 to 90 J/cm2 were used, predominating the values from 1 to 5 J/cm2 . One study did not cite the dose value used.48 The biological effects promoted were reduction of inflammatory cells, increased proliferation of fibroblasts, stimulation of collagen synthesis, angiogenesis inducement and granulation tissue formation. It was noted in a study that the dose of 4 J/cm2 was more effective than 8 J/cm2 .14 Furthermore, doses of 10 and 16 J/cm2 promoted inhibitory effects.20,25,29,34
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