Effect of pulsed ultrasound toothbrush on Streptococcus mutans biofilm removal

Purpose: To evaluate the effect of pulsed ultrasound toothbrush on the removal of biofilm formed by Streptococcus mutans (S. mutans). Methods: S. mutans biofilm grown on apatite pellet was destructed with four different sonic action toothbrushes: 1) pulsed ultrasound with sonic vibration (PUV), 2) continuous ultrasound with sonic vibration (CUV), 3) sonic vibration only (SV), and 4) no ultrasound nor sonic vibration (control). After 3 minutes of noncontact brushing, the amount of water-insoluble glucan was measured, and the residual biofilm was observed by scanning electron microscopy. Results: PUV group revealed the smallest amount of the residual water-insoluble glucans (32 +/- 19%), followed by the CUV group (54 +/- 12%) and the SV group (64 +/- 13%). The PUV group showed a significantly lower amount of the residual water-insoluble glucan than the SV group, while no significant difference was found between SV and CUV. The bacterial adherence and aggregation notably decreased in the PUV group, compared to the remaining three groups.