| 摘要 |
A hand-held rotary brush is provided with a handle, a brush head having a hollow space, a tuft of bristles mounted onto a rotary device which is loosely set within the hollow space of the brush head. When the user manually pushes the brush, a frictional force is created which propels the bristles to catch the irregular surface of the teeth, gaps, causing the rotary device to turn to a circular rotating motion. The construction of the rotary brush can be improved by configured the rotary device with tracks and grooves, which sets within matched grooves and tracks of the hollow space to create a rotating path, that allows the rotary device to rotate within the hollow space of the brush head.
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