If what I'm understanding here is true, you'll be perfectly fine. It sounds like you had the root canal therapy (the removal of the nerve from the tooth) in the past, and then the tooth was built up, but a permanent crown was not placed at that time. Then I'm guessing that some time had passed and a piece of the tooth broke off (the event that got you back into your dentist's office). It then sounds like your dentist replaced the filling material that broke off at your last visit. Your next visit sounds like what will be the crown preparation visit (the tooth is "shaved" down to allow for spaced for the permanent crown, an impression of the tooth is then taken and a temporary crown is made and cemented). If that is what's going to happen, alot of times you won't even need anesthesia (novocaine) for the visit(there is no nerve in the tooth), and most of the time the visit from start to finish will take about an hour. You'll have minimal if any pain afterwards (maybe some mild tenderness of the gum adjacent to the tooth), and the only dietary restriction will be nothing too sticky on the side where the temporary crown is, since sticky foods can pull the temporary crown off as the cement that holds it in place is quite weak (this is so that in a couple of weeks when the laboratory has fabricated your permanent crown that the temporary can be removed and the permanent crown cemented with a much stronger cement).
If this is what you're having done, don't worry at all about it, its much, much easier than the root canal treatment that was already done to the tooth!
