Removal of oral biofilms by bubbles: the effect of bubble impingement angle and sonic waves

Previous research showed that the collision of bubbles with biofilm could remove biofilm from a surface. However, the effectiveness of biofilm removal by bubbles and sonic waves had not been determined.

The authors mounted Streptococcus mutans biofilms in a chamber containing artificial saliva and exposed them to bubbles and sonic waves. They generated sonic waves via an oscillator at the frequencies and acoustic intensities of sonic toothbrushes. They also mounted biofilms at different angles to measure the effect of a bubble's impingement angle.

The presence of sound had no significant effect on the amount of biofilm removed (F = 0.51). There was no statistically significant difference in the amount of biofilm removed with respect to the angle at which bubbles impinged on the biofilm (F = 0.65). The authors performed analysis of variance tests to determine whether the difference in the amount of biofilm removal was significant (F < 0.05) in the presence or absence of sound and at the different angles tested.

The collision of a bubble at any angle between 5 and 45 degrees was equally effective in removing biofilm. The addition of sound to a bubble stream at the tested intensities had a negligible effect.

Bubbles produced by dental instruments are effective in removing biofilm from the surface of the teeth, regardless of the angle at which the bubble impinges on the biofilm.