Ultrasound is just gentle air vibrations/oscillations, not audible, not visible and not perceptible.
No ultrasound is really safe to use. The ultrasound generated for Dogs is not comparable to the hard ultrasound used by dentists and veterinarians. Versions of this technology have been used on humans for over 20 years.
With some/ most toothpaste the most active ingredient are the abrasive particles. Our toothpaste doesn't contain any abrasive particles. With a typical toothbrush whether a power sonic toothbrush or a manual brush results occur by scrubbing/rubbing the teeth and gums hence abrasive particles are necessary. On the other other hand, with the toothpaste for Dogs that we use, ultrasound air/wave oscillations that are generated which blow away/kill germs and bacteria as well as small food particles. Our toothpaste generates nano-bubbles which aid in the destruction of the germs and bacteria. Further, the ultrasound waves penetrate through some layers of gums to harm germs & bacteria. Similar forms of this technology has been used on people for over 20 years. It has been proven safe and effective.