1Description of light therapy technology
There are a number of different types of laser used for medical purposes, including crystalline laser medium, semiconductor lasers, liquid lasers and gas lasers. The carbon dioxide, argon, and neodymium: Yttrium Aluminum Garnet (YAG) laser have found many applications in the surgical field. Such lasers often operate in the 10 to +100 mW range with subsequent ability to vaporize and coagulate tissue.
Light therapy or “cold” lasers use radiation intensities so low that it is thought that any biological effects that occur are due to the direct effects of radiation rather than the result of heating. Energies delivered are typically about 10 joules per cm2, using lasers operating at powers of 50mW or less. Light therapy devices have been advocated for relief of pain, healing of soft tissue disorders, and treatment of peripheral neuropathies and primarily include the gallium-aluminum (GaAL), gallium-arsenide (GaAs), gallium-aluminum-arsenide (GaAlA) and helium-neon (He-Ne) laser. The He-Ne laser was the first laser available and is reported to have beneficial effects in both dentistry and wound healing. The advantage of He-Ne laser is that it emits red light, which is visible and therefore the blink reflex protects the eye from it. The GaAs and GaAlAs laser have been most commonly used for the treatment of pain and inflammation and in lower doses for wound healing as they have deeper tissue penetration than the He-Ne laser. The disadvantage of these lasers is that their light is invisible and therefore eye protection is required.
It is hypothesized that by exposing cells in a wound to the photon energy from Light therapy, the repair is enhanced by cellular proliferation or migration. A number of mechanisms of Light therapy have been postulated including ATP synthesis, collagen synthesis, fibroblast proliferation, phagocytosis of macrophages, activation of the immune system and acceleration of the inflammatory phase of wound healing.