Bactericidal action of 308 nm excimer-laser radiation: an in vitro investigation

The aim of the present study was to investigate the influence of 308 nm excimer-laser radiation on bacterial growth. Six different bacterial strains (Staphylococcus aureus, Escherichia coli, Streptococcus faecalis, Lactococcis lactis, Salmonella typhimurium, and Deinococcus radiodurans) were exposed in vitro to various doses and energy densities of laser radiation. To exclude bacterial killing by supraphysiological heating, the temperature change in the samples during irradiation was measured. Extended antimicrobial effects of XeCl excimer-laser radiation depending on the time of radiation, the energy density of the laser beam, and the irradiated bacterial strain were observed. Reduction of bacterial growth is independent of temperature and not linked to any ablative tissue removal. In almost all cases, a 99.9% reduction of bacteria was reached by total radiation times < 100 ms. The proven antimicrobial effects of 308 nm excimer-laser radiation may be of significant clinical importance in endodontics and periodontology in the future.