At the time there was a guy named Bob Jones who devised a machine that could see cavitations using Sonar.
My holistic dentist used it on me. This machine would bounce these signals off the jaw bone. If these was no bone it would send back a different signal.
Aetna Insurance took them to court over payment for this service and won.
My Dentist lost his dental licence in my state, and moved to Oregon.
Last I heard Bob Jones moved to Texas. Not sure about the status of the "Cavitat Machine"