The principle behind LAD, so-called photodynamic therapy (PDT) has been known for over 100 years.
The concept behind the PDT has been thoroughly tested throughout the last 10 years, partly with lasers and partly with LED light. LAD is particularly interesting because the concept can be used for treatment of as many different micro organisms as there are cases. Dortbudak (2001) showed a significant reduction in the number of Actinomyces actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia after treatment with PAD (TBO+690nm LED) on 15 patients with periimplantitis. Haas (2000) also showed on 17 patients with periimplantitis that PAD was able to reduce the inflammation.Kömerik et al (2003) showed in a rat model, where the rats were inoculated (on each side of the maxillary molars) a dissolution of Porphyromonas gingivalis, and was subsequently treated with 630 nm laser light resulting in: 1. No surviving bacteria in the group treated. 2. On histological examination no negative effects were found with PAD. 3. After 90 days there was significantly less bone resorption in the group with TBO+laser compared with the control group (no treatment or TBO and laser respectively). Sigusch et al (2005) showed, in a model with beagles where these were infected with Porphyromonas gingivalis and Fusobacterium nucleatum subgingivally around all teeth that the PAD treatment resulted in significantly less reddening and tendency to bleeding. Shibli et al (2003) showed in a model with a ligature induced periimplantitis in dogs that PAD reduced the number of bacteria of Prevotella strains, Fusobacterium strains and Streptococcus betahaemolyticus. Furthermore, Shibli (2006) showed in dogs with periimplantitis, that PAD together with guided bone regeneration (GBR) gave better results than GBR alone. Teichert et al (2002) showed in a model with immuno-suppressed mice that PAD could totally eradicate Candida albicans from pseudomembranous candida lesions on the back of the tongue. Bonsor (2006) showed in an examination of 14 patients and 32 root canals in clinical practice that 20 root canals were initially infected.