I am with you all the way bid767 - just in from dentist on Friday - with exact thing as you - like you I was terrified he broke the post but he "knocked me out" - twilight sleep - drilled into back of crown which I thought could not be done but anyway there was "pus"/pressure - he released the pus and he told me he took "the bad nerve" probably from the post (your nerve is away up in the gum at the top of post - that I know) and the pressure on the tooth has gone down. He took a cuppla x-rays. Having said that I have to back in March to get second treatment - bless him - he did explain but I could not take it in. I think it will be to clean the crown up. Like you FRONT TOOTH - you will do anything to keep it. I would say your crown has dropped down and sensitivity is there or infection - he will take an x-ray and he will take it from there. Let me how you get on. - good luck