A testing system for electric toothbrushes

Purpose: To assess in vitro the contributions of mechanical and acoustic mi crostreaming forces around electric toothbrushes to remove cheese using an experimental model. Materials and Methods: Four toothbrushes, Braun Oral-B Plaque Remover (D7), Braun Oral-B Ultra Plaque Remover (D9), Interplak (IP) & Sonicare (SC), were investigated. A model system consisting of a layer o f 0.2 mm thick cheese was applied to a microscope slide. The toothbrushes w ere operated in contact with the slide under loads of 0.3 N dry or with the bristles immersed in 2 mm of water. Turbulence around the moving head was assessed with the bristles placed non-contacting, 1 mm above the slide. An experiment with contact for 2 seconds and then 10 seconds non-contact was a lso made. The slides were stained and image analyzed. The area of removal w as measured together with the "average cleaning/brush contact unit area" (t he area of removal was divided by bristle contact area). Results: The remov al pattern varied. D9 and SC were efficient when operated dry. When the bru shes were operated in water, the D9, SC, and IP were efficient in removing the cheese. With no contact, SC produced disruption of the cheese layer whi le the other brushes did disturb the surface but did not remove completely the cheese. This disturbance without removal was not recorded by image anal ysis. When the vibrating brushes were allowed to touch the medium and then moved away, a large amount of removal occurred. Larger amounts of removal t ook place with the D7, D9 and the SC. The use of brushes with a larger head and bristle contact produced a larger area of removal. However, when the " average cleaning/brush contact unit area" was used, the smaller headed brus hes produced a larger amount of removal relative to their size. These diffe rences in the removal characteristics between the four electric toothbrushe s in vitro suggest that such a model system may prove useful in testing suc h devices before they are assessed clinically.