Hello! My grandmother's dentist told her that she needs to have a root canal on 3 teeth.
My opinion is that she get a second opinion preferably from a holistic dentist
The pain indicates there is a problem, but the holistic dentist will determine to what extent, and advise on any needed treatment.
If he recommends removal, he will do it in a proper way. You didn't mention if the teeth had fillings in them that contain mercury, but that dentist will remove them making sure she doesn't consume any of the mercury.