In Finland there is a profession called dental hygienist, whom I visit once a year. They clean up my teeth with an ultrasound device since many years, removing tartar.
That's called an ultrasonic scaler, which is quite different to the device in the article. A scaler is for removing tartar and stain while the device in the article is an ultrasound (like the device for viewing babies during pregnancy) which looks under your gums at your tooth roots and bones to see if you have any bone loss or gum disease.
You might not have the dentist or dental hygienist use the probe very often. When they do it's a rounded straight tip device, and they usually call out numbers to an assistant for how deep under the gumline the probe can reach. That's the procedure this device would replace. If nothing else it's an improvement because you don't need an assistant to record the numbers, and if someone has bad gum disease it might hurt them when you poke in there with a probe.
I went 14 years between dental visits, and the move to ultrasound cleaning was the biggest change I noticed. The cleaning had always been a bloody affair, scraping and scratching in a way that would leave me with a throbbing pain after my appointment was ove. The ultrasound cleaning was like science fiction.
In the US most visit that person twice a year. They have that ultrasound machine, but they only use it on people who don't visit that often - the machine just gets the build up do the point where manual tools can finish the job. If you brush/floss and visit regularly the manual tools are all they need.
In this was at least it looks like the US system is better. Of course there is no way nuance can be expressed in a short forum like this, but maybe you need to look at the Finland system to see if it is really good enough.
For the patient with an ultrasonic scaler in their mouth, are you saying that that a significant percentage of harmful noise is coming in through the ear canal, so conventional ear protection would help?
I would not call it exactly painless though.