There are many types of post designed available for post and core systems, utilizing various combinations of the following properties:
Types of Posts
1. Pre-fabricated Posts: These are available in different sizes and designs by various manufacturers. A suitable post can be selected according to size and shape of the prepared root canal. The procedure of placement of these kinds of posts is less complicated so; they are most commonly used ones.
2. Custom made Posts: For these posts, after removing gutta-percha from the root canal, the impression of canal is taken by using inlay wax. This impression is then sent to lab for the fabrication of post. Then in the next appointment it is cemented in the root canal so, more number of visits are required for its placement. The advantage of these posts is that they conform to the shape of root canal more accurately as compared to pre-fabricated posts.
According to Shape
1. Parallel post having its walls parallel to each other
2. Tapered post having tapered walls
Threaded Parallel Sided Post
Parallel posts are better as compared to tapered ones in their retention but it is more difficult to prepare root canal for placement of parallel posts and a little amount of more tooth structure has to be removed from the root to make its walls parallel to receive a parallel post.
According to Surface Design
1. Smooth: It is less retentive as compared to both serrated and threaded posts but root is not subjected to excessive forces when it is cemented in the root canal. It is the ideal type of post to be used in a long properly shaped root canal.
2. Serrated: It is most commonly used. It also fits in the root canal passively and is more retentive as compared to smooth surface post.
3. Threaded: It is most retentive as it engages the dentinal wall of the root canal actively as it is screwed in the root. But as it is screwed into the root canal, excessive forces are generated in the wall of the root which may fracture the root. So, this design is contraindicated most of the times.
According to Type of Material Used
Post can be made from
1. Metal: Gold or Base metal alloys
2. Stainless steel
3. Carbon fiber
5. Optical fiber
Stainless steel Post Fiber Post
The post made up of fiberglass such as optical fiber is a new invention. This type of post is flexible and it conforms to the curved contours of the root canal. So, there is less mechanical weakening of the tooth structure when this post is used.