**4. Objective**

cases. Different LLLT protocols have been widely used in numerous medical situations with

In this review, the author characterized eligible papers into in vivo and in vitro experimental studies and clinical trials that evaluated the use of LLLT on skin wounds for promotion of healing. The author conducted an electronic search of scientific peer reviewed papers in the PubMed database of English language studies published from 2004 to 2016 with the keyword "low‐level laser therapy." As inclusion criteria, the author chose articles with availability of access to the full text. This review intended to show the positive effects of LLLT on healing of skin wounds, diabetic foot ulcers, and burns. Initially, the author introduced wounds, ulcers, and burns and showed their importance. Next, a number of important related papers in the

Devices that provide light amplification by stimulated emission of radiation (LASERS) typically generate electromagnetic radiation of a uniform wavelength, phase, and polarization. In 1960, Theodore Maiman has originally described a ruby laser. A laser is described as a source

The term "LLLT" is broadly applied to the therapeutic effects of lasers; other terms, such as low power laser therapy, laser biomodulation, laser bioactivation, laser biostimulation, laser irradiation, and laser photostimulation, may be substituted for LLLT. In this review, the author have chosen the term LLLT photostimulation because of the observed stimulatory effects of the laser beam and photochemical nature of its interaction with biological systems. LLLT is a special type of laser that influences biologic systems through nonthermal means [2]. The use of LLLT as a therapeutic modality has originated from Eastern Europe approx‐ imately 50 years ago [2]. In 1967, Professor Mester, an employee of Semmelweis University in Budapest, Hungary, observed that applying laser light to the shaven backs of mice could cause more rapid regrowth of hair compared to unshaven mice [3]. He reported that the helium‐neon (He‐Ne) laser had the capability to promote wound healing in mice [4]. Professor Mester applied these findings to humans when he used lasers to treat patients with nonhealing skin ulcers [5, 6]. The clinical applications of LLLT have become the leading edge of clinical research in several countries, such as the former USSR, Japan, Canada, Australia, United Kingdom, China, and several Scandinavian countries. The history, origin, and development of various lasers are well authorized [2]. The clinical application of laser photobiostimulation is growing rapidly. Several review articles that explain the clinical applications of LLLT have been published [2]. LLLT is currently considered not only as a therapeutic procedure primarily used for relief of inflammation, edema, and chronic joint

the intent to accelerate the regenerative processes of tissues.

400 Wound Healing - New insights into Ancient Challenges

field were reported.

**2. Definition**

**3. History**

of light or radiation energy [1].

LLLT exposes tissues and cells to low levels of red and near infrared (NIR) and IR light. This treatment is introduced to as "low level" because of usage of light at lower energy densities in comparison to other types of laser therapy such as cutting, ablation, and thermal coagulation of tissue. LLLT is also defined as "cold laser" therapy because of the lower power densities used compared to those needed to produce tissue heating [7]. LLLT is currently used to treat a wide variety of diseases in which a large number of laser parameters such as the energy density, wavelength, pulse structure, power density, and timing of the applied light must be chosen for each treatment. A less than optimal choice of parameters can lead to not only reduced effectiveness of the treatment but also result in negative therapeutic outcomes. Thus, numerous published results on LLLT include negative findings simply because of an inap‐ propriate choice of light source and dosage. This choice is particularly important because of the optimal dose of light needed for any particular application; doses higher or lower than this optimal value may have no therapeutic effect. LLLT is defined by a biphasic dose response: lower doses of light are often more advantageous than high doses [7]. This review aims to discuss the positive effects of LLLT on healing diabetic wounds and burns. Low‐level laser energy density (J/cm2 ) calculation: power (W) × duration of laser radiation (s)/laser beam surface area (cm2 ).
