Doctors don't have cavitat machines. There's only a handful of dentists in the world that have them. Theres 2 in the UK that I am aware of. The first guy i went to see wasn't an oral surgeon at all, so not really sure why he has a scanner since he can't do anything anyway. But he did a scan of my entire lower jaw, which really was needed as you just can't access the scale of the damage unless this is done. Ie in my case the cavitation from my wisdom teeth had spread to the next 2 adjacent teeth, one of which I had to lose.
It sounds basically like you need to find another dentist. If the bone around a tooth has died, it's not going to ever magically remover, in fact it'll probably just slowly spread and get worse over time.