Some of the basic concepts of low level laser therapy Review

Keywords: Time:17-05-2016

The first working laser was presented to the public at a press conference in late 1960’s by Theodore Maiman.2 He demonstrated a ruby laser. The potential for using lasers for surgery was soon explored and rapidly introduced into surgical suites in many countries throughout the world. A Hungarian physician named Endre Mester performed cancerous tumor treatment experiments on rats utilizing laser. He found that because it was underpowered for that purpose, the laser he was using didn’t kill tumor cells but, instead, accelerated wound healing in the surgical sites of the experimental rats.3 He is the grandfather of photobiomodulation since he was the first to observe the healing effects of low powered lasers. To date, there have been more than 2500 published studies worldwide involving low level laser therapy with approximately 120 double blind studies published.4 Ther e are several extraordinary effects that have been observed with therapeutic lasers, and phototherapy in general, that make laser therapy unique among the various healing modalities available today. Photobiomodulation produces changes in oxidation/reduction status of the mitochondria which lead to dramatic increases in ATP synthesis. Activation of the sodium/potassium pump alters the cell membrane permeability to calcium 5 (see Figure 1). Phototherapy has been shown to effect cellular activity in the following ways:
• stimulates cell growth
• increases cell metabolism
• improves cell regeneration
• invokes an anti-inflammatory response
• promotes edema reduction
• reduces fibrous tissue formation
• stimulates nerve function
• reduces the production of substance P
• stimulates long term production of nitric oxide
• decreases the formation of bradikynin, histamine, and acetylcholine
• stimulates the production of endorphins.

These photo-biological responses are largely responsible for the pain relieving effects often observed in patients treated with phototherapy. There are three effects that commonly occur as a result of tissue exposure to light photons. They are:

Primary effects of photoreception are a result of the interaction of photons and cell mitochondria which capture, direct, and transduce photon energy to chemical energy used to regulate cellular activity.

Secondary effects occur in the same cell in which photons produced the primary effects and are induced by these primary effects. Secondary effects include cell proliferation, protein synthesis, degranulation, growth factor secretion, myofibroblast contraction and neurotransmitter modification—depending on the cell type and its sensitivity. Secondary effects can be initiated by other stimuli as well as light.

Tertiary effects are the indirect responses of distant cells to changes in other cells that have interacted directly with photons. They are the least predictable because they are dependent on both variable environmental factors and intercellular interactions.