I can't speak to your problem directly, but I can offer one piece of advice regarding prevention of the need for a root canal and crown. Don't eat Pork Picnic Shoulder Chops. The little bones can easily cause a cracked molar, or, in my case, two. Of course, I am one of the rare people who have four nerves in each of the lower large molars and guess what. The bastard charged me extra for the "extra" nerves. The nerve!!!