Can I still have a crown when there is no tooth?

Hi:As long as there is a 4-6 mm of buildup or tooth structure a crown can be placed.  Best,Dr. Maddahi

The crown is placed on a substructure that is strong enough to bear chewing functional load. It can be a reduced tooth, a post or an implant abutment if the tooth has been lost. I suggest you to call your dentist to have the temporary crown re-fabricated since some changes may take place while your new crown is being made. Such changes may alter the fit and sometimes even a gum contour. Good luck, Dr. Daniyar

If the post is secure then composite build-up material can be bonded to it and to the the root that the post has been bonded to. As long as there is enough root surface above the bone and the build-up is done well a crown can be placed.