Effects of dynamic fluid activity from an electric toothbrush on in vitro oral biofilms

Objectives: To determine the plaque-removing ability of a Sonicare Plus((R)) electric toothbrush in an in vitro model. Material and Methods: Multispecies oral biofilms derived from human saliva were grown on hydroxyapatite discs in a constant-depth film fermenter. The biofilms were placed in a typodont model so that they mimicked the interproximal plaque between teeth 46 and 47 and were then treated with an electric toothbrush, both activated and inactivated. The distance from the bristle tips to the edge of the disc was 2.65 mm. Brushing action was controlled by a specially constructed brushing machine. After brushing, the number of viable bacteria removed from, and remaining in, the biofilms were determined. Results: In all, 73.70% of viable bacteria in the biofilms were dislodged from the discs using the activated toothbrush. An inactivated toothbrush removed only 3.66%. Scanning electron microscopy and confocal microscopy revealed differences between untreated and treated biofilms. Conclusion: The fluid shear forces generated by the electric toothbrush penetrated at least 2.65 mm beyond the reach of the bristles and these forces contributed to the toothbrush's plaque-removal ability (p <0.001).