Effects of iron-oxide nanoparticles on compound biofilms of Streptococcus gordonii and Fusobacterium nucleatum

The human mouth is a host of a large gamut of bacteria species, with over 700 of different bacteria strains identified. Most of these bacterial species are harmless, some are beneficial (such as probiotics assisting in food digestion), but some are responsible for various diseases, primarily tooth decay and gum diseases found in gingivitis and periodontitis. Dental plaque comprises a complicated biofilm structure that varies from patient to patient, but a common factor in most cases is the single species of bacterium acting as a secondary colonizer, namely Fusobacterium nucleatum, while the actual disease is caused by a variety of tertiary colonizers. We hypothesize that the destruction of a compound biofilm containing F. nucleatum will prevent tertiary colonizers from establishing a harmful biofilm, and thus will protect the patient from developing gingivitis and, consequently, periodontitis. In this paper, we report on the effects of exposure of compound biofilms of a primary colonizer Streptococcus gordonii combined with F. nucleatum on a hydroxyapatite substrate to iron oxide nanoparticles as possible bactericidal agent.