I have a question, recently my wife has had a bad toothache so she went to the dentist and they found that a different dentist 12-13 years earlier had left a part of an instrument embedded in her tooth/crown while doing a root canal. The x-ray shows this metal spike as clear as day, now it seems that she is going to have to have a not so simple procedure to get the thing removed. I think the previous dentist should cover the costs of the procedure, am I wrong?

What should our course of action be?