ULTRASONIC TOOTHBRUSHES, WHICH USE ULTRASONIC WAVES TO CLEAN THE TEETH

The newest developments in this field are ultrasonic toothbrushes, which use ultrasonic waves to clean the teeth. In order for a toothbrush to be considered “ultrasonic” it has to emit a wave at a minimum frequency of 20,000 hertz or 2,400,000 movements per minute.
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