I know all about that. I've seen two dentist who said that I needed a rootcanal treatment. I told them that there was someting sharp in my lower gums. Ofcourse this wasn't possible. "You really need a rootcanal treatment". Both times I refused to do that, because I knew something else was going on. Not so long ago there was an abcess in my gums and a couple of days later, a piece of composite ( from my fillings on front teeth !) came out of my gums. One month later it happend again and another piece came out. I made pictures from it with my microscope. You should have seen the dentists face when I showed the pictures. ( http://wp.me/p1tqIo-w3
) A rootcanal treatment would have been completly useless.