Prefabricated post and cores take less time to place compared to cast post and cores; they can be inserted immediately after the endodontic therapy has been completed. Normally, prefabricated post and cores can be inserted in a single appointment.

1. Post selection

Prefabricated posts come in a range of sizes and shapes : the first step is to select the post that best fits the clinical application.

A prefabricated post system contains posts at (at least) 6 different thicknesses and 3 different lengths. Moreover, the surface of the posts can be smooth (for example, in case of a fibre reinforced post system) or threaded (in case of metal screw posts).

metal screw posts of various sizes

fibre reinforced post system

As a classic rule in prefabricated post and core design, it is advisable to utilize the narrowest and longest post possible with a smooth surface. This design will decrease the risk of failure.

• Utilizing the longest possible post ensures that the forces transmitted from the crown are distributed over as much of the root as possible

• Using the appropriate diameter post ensures that as much natural tooth structure as possible is left to support the post and absorb the transmitted forces.

• A smooth-surfaced post, although less retentive as it simply lies within the post space after being cemented, transmits the least amount of force to the root structure.

• A threaded post is actively screwed in, and, while being the most retentive by far, it produces a high amount of force on the brittle root structure.

2. Root canal preparation

The root canal is prepared by using progressively wider endodontic files until the desired shape is achieved. The last file that is used will have to match the selected post dimensions.

3. Post insertion and cementation

The post is inserted into the post space :

• Screw posts are actively screwed in with specific screw-keys

  

  screw post and screw key

• Smooth-surfaced posts are cemented inside root canals with composite materials or dental cement

  

  fibre reinforced post prior to cementation

4. Core material build up

After the prefabricated post is properly cemented into the post space, a core material, normally dental composite, is packed around the cemented post.

After the composite has been cured, further adjustments can be made to shape the core into a crown preparation. After that, an impression is taken for the fabrication of the prosthetic crown.