They all follow a similar procedure, in which special drills are used to prepare a space down the widest canal in the tooth, (if there is more than one!) The longer the post i.e. the further it goes down, the more retention there is for the filling on top, but it's important to leave at least 5mm of root filling (Gutta Perche) at the bottom in order to keep the canal sealed.
The dentist will take an X-ray
to see how far down the post is and to check the post is in-line with the canal. Once satisfied, the post will be stuck in place and the filling material built up around it- if it is of the prefabricated type (usually composite). When the dentist does this- it is called a direct
post and core because they complete it directly there and then.
The dentist may decide that a custom- made post and core is best; it may just be their preference or because of a very wide or awkward shaped canal. This is an indirect
method and involves taking an impression of the canal space using an impression post with impression material over the top and sending it off to the lab.
The lab will then construct your custom-post, meaning it is custom- made for your particular canal (either in wrought metal or cast metal). They will then return it to the dentist for sticking in. When made in this manner, there is no need to build up filling material on the top before placing the crown, as the post and the core come as one piece.
Sometimes the crown will also be made at that appointment and everything can be cemented in at the next visit, or maybe, the post will be cemented and a new impression taken- on which the crown will be made. The latter, has given a more consistent result to me personally, but it does mean an additional appointment will be needed to get the treatment completed.
Any tooth having a post, will need a crown on top to protect it.