Sonic toothbrushes use two types of cleaning actions. Mechanical scrubbing – This is like other kinds of toothbrushes and depends on how far the brush head travels on each stroke as it makes contact with tooth enamel. This side-to-side brush travel distance of sonic toothbrushes is called amplitude.  Fluid Dynamics – Fluid dynamics is the process where the vibrations of the toothbrush bristles vigorously agitate and drive fluids such as TartarEnd and saliva beyond the tips of the bristles. A high-amplitude sonic toothbrush head, vibrating at 30,000 vibrations per minute, will drive fluids further between the teeth and below the gumline than a low-amplitude sonic toothbrush vibrating at the same speed. Fluid dynamics have been shown to clean tooth enamel well beyond the tips of the brush head bristles. Amplitude is not normally listed as a specification for sonic toothbrushes. Toothbrush manufacturers normally list vibrations per minute but not amplitude. TartarEnd LLC has studied numerous toothbrushes vibrating about 30,000 vibrations per minute, and we find that a simple test in a glass of water is a good method of visualizing amplitude. The video on the oral care tab of the website shows an inexpensive sonic toothbrush with high amplitude. This video shows a Philips Sonicare Series 4100 toothbrush fitted with a compact brush-head set at its high speed setting. The tartar and plaque dissolving and removing abilities of TartarEnd toothpaste show the importance of non-contact fluid dynamics of high amplitude sonic toothbrushes.