What is a build out as opposed to a root canel?

I had my 4 front teeth prepared for crowns and two teeth (I was told) would need crowns at a later date if I did not have a build up done at the time of the preparation. Well let me tell you that I have been sick with infection ever since that and I can not get rid of the infection which is in the tissue behind my nose and roof of my mouth. This is going on 3 1/2 months now and I am about to finish my 4th round of antibiotics, each prescription being stronger than the last and this time I had steroids to go along with the mix. I am losing hair, my skin is dry and flaky, my nails dry and brittle and my body is about worn down. I have spent a great deal of money on doctors, emergency room visits and medications and now my dentist is beginning to finally admit that there may be something to all of this. In the last two weeks at his expense, he has sent me to a Periodontist, I have a cone CT Image, etc., a radiology report and yesterday he paid for me to see an Endodontic. This doctor thinks that my original dentist should have done a root canal in the first place instead of a build-up. Can you give me some insight to this please? I am getting married on Saturday and I am now finished with the Steroids and Antiobitocs and feel myself getting sick again and it is Wednedsay evening. Any feedback will be greatly appreciated. Kind regards, Carol Heuman carolaheuman@yahoo.com 305-582-3962