If he has teeth that are in bad shape or gum disease they will typically pull the teeth to avoid ORN. If his teeth are healthy and he has no gum disease then you can debate them on this. 4 teeth doesn't seem to be too bad. Some of us have lost all of our teeth, most of us just the molars and teeth in the radiation field. There have been other recent posts on this very subject - do a search on teeth and I am sure you will get an earful about this controversial subject. Some of us, like myself, refused to have teeth pulled.