I had a root canal done and then a post and core put in without a crown. It has been a few years since this was done. Today while not even eating anything, the whole tooth, post, and core fell out! It is the top first molar so it is sort of right in between my teeth. Is this common for the whole thing to just fall out??? I mean the post shouldn't do that, should it?? I thought that was cemented in? What are my options now? I have broken off tooth at the gum line - is an implant my only option (aside from having the remaining part of the tooth under the gun line removed)? Should my dentist be responsible for this failure???