RESUMO
BACKGROUND: Oxygen is generally considered essential for lethal photosensitisation by photodynamic processes. The oral anaerobes, Prevotella intermedia and P. nigrescens are known to be photosensitive, but are also extremely sensitive to the cytotoxic effects of oxygen. METHODS: The Prevotellaceae were exposed to two 405 nm light sources for different exposure times in an anaerobic chamber. Viable counts of the light exposed samples were compared to light-free controls to determine the proportion of bacteria killed. RESULTS: Lethal photosensitivity was demonstrated against P. intermedia and P. nigrescens. The proportions of bacteria killed by either the light-emitting diode or laser pointer were similar at a given energy density (J/cm(2)). CONCLUSIONS: Lethal photosensitivity was demonstrated in two species of Prevotella under anaerobic conditions.