I would call that dentist right back and insist on getting in today to have the rest of the tooth removed. I would also question them as to whether or not they plan to bill you for the visit as they charged you for the previous visit and ensured you there was no crack in the tooth. I would let them know that you would appreciate not being billed for this visit as it should have been taken care of in the first visit. It is hard now I think with the equipment that the dentists use. I had a cavity that I could see between two of teeth in the front and when I went and had xrays done the dentist found two others but never mentioned that one. I questioned him about is and he said that it definately was a cavity and was quite disappointed that his new high tech machine did not show it. He just shook his head as it had happened to him a few times before. For some reason this great new technology they have is not really that great. Good luck to you.