Removal of Streptococcus mutans biofilm by bubbles

BACKGROUND: Air bubbles had been shown to remove particles and bacteria from surfaces, but they had not yet been studied regarding the removal of mature biofilm from a surface. METHODS: Streptococcus mutans were grown as a biofilm on glass coverslips and were exposed to a fluid stream with or without bubbles. Three parameters (stream velocity, gas fraction, and bubble size) were varied in the bubble stream to determine which conditions best remove the biofilm. RESULTS: At low velocities bubbles enhance biofilm removal compared with the liquid alone. Stream conditions that were shown to be the most effective in removing biofilm were large bubbles at low gas fractions. CONCLUSIONS: These results suggest that flowing bubble streams may be a desirable feature to incorporate into oral hygiene products to remove accumulated biofilms such as dental plaque.