from LASER WORLD (Swedish LASER Medical Society)
Q: What is laser therapy?
A: Laser therapy or Laser Phototherapy is a method where light from a laser is applied to tissue (or cells in culture) in order to influence cell or tissue functions with such low light intensity that heating is negligible. The effects achieved are hence not due to heating but to photochemical or photo-biologic reactions like the effect of light in plants. The lasers used are normally called therapeutic lasers or medical lasers. This is in contrast to the use of lasers in surgery and for aesthetic purpose where strong lasers are used and where the biologic effects (cutting, evaporating, coagulating) are based on heat development from the absorption of strong light, i.e. burning glass effect.
Q: Is laser therapy scientifically well documented?
A: Basically, yes. There are more than 130 double-blind positive studies confirming the clinical effect of LLLT. More than 3000 research reports are published. Looking at the limited LLLT dental literature alone (370 studies already in 1999), more than 90% of these studies do verify the clinical value of laser therapy. About 250 papers are annually published in peer reviewed scientific papers.
Q: Can LLLT cause cancer?
A: The answer is no. No mutational effects have been observed resulting from light with wavelengths in the red or infra-red range and of doses used within LLLT.
Q: Are there any contraindications?
A: There are no medical contraindications. In most countries there are legal contraindications, i.e. you should not treat cancer or some other serious diseases. Pregnancy is not a contra indication if treatment is done with common sense. Pacemakers are electronic and are not influenced by light. The most valid contraindication is possible lack of adequate medical treatment.
Q: Does the coherence of the laser light disappear when the light is scattered in the tissue?
A: No. The length of coherence, though, is shortened. Through interference between laser rays in the tissue, very small "islands" of more intense light, called speckles occur. These speckles will be created as deep as the light reaches in the tissue and within a speckle volume, the light is partially polarized. It is easy to show that speckles are formed rather deep down in tissue and the existence of laser speckles prove that the light is coherent.
Further information from THOR Laser