ABSTRACT
The first publications about low-level laser therapy (LLLT) (then called laser biostimulation) appeared more than 40 years ago. Since then, more than 4000 studies have been published on this still-controversial topic (Tuner and Hode 2010). In the 1960s and 1970s, doctors in Eastern Europe, and especially in the Soviet Union and Hungary, actively developed laser biostimulation. However, scientists around the world harbored an open skepticism about the credibility of studies stating that low-intensity visible-laser radiation acts directly on an organism at the molecular level. Supporters in Western countries, such as Italy, France, and Spain, as well as in Japan and China, also adopted and developed this method, but the method was-and still remainsoutside mainstream medicine. In the past several years, some excellent experimental work was performed in the United States (Anders 2009; Eells et al. 2003, 2004; Pal et al. 2007; Wong-Riley et al. 2001, 2005; Wu et al. 2009). The controversial points of laser biostimulation, which were topics of great interest at that time, were analyzed in reviews that appeared in the late 1980s (Karu 1987, 1989). Since then, medical treatment with coherentlight sources (lasers) or noncoherent light [light-emitting diodes (LEDs)] has passed through its childhood and adolescence. Most of the controversial points from the childhood period are no longer topical. Currently, low-power laser therapy-also called LLLT or photobiomodulation-is considered part of light therapy as well as physiotherapy (Karu 2003, 2007). In fact, light therapy is one of the oldest therapeutic methods used by humans [historically as sun therapy and later as color light therapy and
ultraviolet (UV) therapy]. A short history of experimental work with colored light on various kinds of biological subjects can be found elsewhere (Karu 1987, 1989). The use of lasers and LEDs as light sources was the next step in the technological development of light therapy.
