Typically, ultrasonic toothbrushes approved by the U.S. Food and Drug Administration (FDA) operate at a frequency of 1.6 MHz, which translates to 192,000,000 movements per minute.
Pogoj, da zobno ščetko uvrščamo med ultrazvočne, je njeno delovanje v frekvenčnem območju nad 20.000 Hz oziroma 2.400.000 gibina minuto.