Characterising Mechanical, Chemical and Biological Removal of Interproximal Biofilms

Objectives: The build-up of bacterial biofilm (dental plaque) on tooth surfaces is the main contributor to the most common oral diseases of humans, dental caries and periodontitis. Plaque accumulates in ‘sheltered sites’ such as the subgingival margins and interproximal spaces, where it is difficult to remove. Bacterial adhesion in the mouth is somewhat hierarchical; with certain species able to adhere to the acquired enamel pellicle (early colonising bacteria); while others adhere better to established bacterial biofilms. Later colonising bacteria are more closely associated with oral disease. Devices based on combinations of air and water microdroplets have recently been introduced to remove biofilms from difficult-to-reach areas such as interproximal spaces.

The aim of this project is to further improve microdroplet-based biofilm removal by combining it with chemical or biological approaches.
Methods: Biofilms of early colonising bacteria (Streptococcus gordonii, Actinomyces oris and Veillonella parvula) were cultured in an interproximal ‘Typodont’ biofilm model and challenged with the Philips Sonicare AirFloss device. A multiplex qPCR assay was developed for absolute quantification of the three species. The impact of various treatments on biofilms was also measured by cell viability assays, SEM imaging and Live:Dead staining.
Results: AirFloss treatment significantly reduced adherent biofilm approximately ten-fold. By microscopy, the biofilm was almost completely removed from areas directly in the path of the Airfloss. Treatment with selected antimicrobial compounds reduced cell viability.
Conclusions: Overall, these data show that the AirFloss effectively reduces biofilm biomass and indicates that chemical agents can potentially increase the impact of physical biofilm disruption. Further studies will now assess their impact on biofilm composition in more complex systems.