Post and core procedures are done to anchor a crown or stabilize weakened tooth. When tooth structure is inadequate to reinforce a conventional restoration then a small rod or post is inserted into the root space with a few millimeters of protrusion. This protrusion which is the core supports the large crown or filling, whichever is appropriate. The missing coronal tooth structure is replaced sufficiently to restore full functionality and aesthetics of the tooth.
Post and Core Procedure
For a tooth that has already undergone root canal therapy:
- The carious tooth structure and temporary material are removed to expose the distal apical margin to visualize the structure of the tooth
- Caries detection dye will ensure that all decay and debris is removed
- A laser gingivectomy may have to be performed to the apical extent of the decay to visualize the tooth structure
- Probing will reveal if there is any violation of biological width
- Spaces are created for the posts in the buccal and lingual canals and a matrix is placed – post drills finalize the post space
- The posts are placed and cemented using a composite resin which is also used to build-up the core
A final preparation is done for the placement of the crown
Principles of post placement
- Root canal system contamination should be avoided
- Healthy tooth structure should be well-preserved
- After completion of the root canal tooth should be restored as soon as possible
- Posts should be used only for a core build-up
- Minimum 4 mm of gutta-percha should be left at the apical end (this is determined with the help of radiographs)
- The length of the post (below bone crest) = height of tooth (above bone crest)
Types of post and core
- Prefabricated post and core: Prefabricated post and core do not involve any laboratory work and are easy to place. These can be inserted immediately as soon as the endodontic therapy is completed which reduces the time for placement. Prefabricated post and core come in different ranges and sizes and the best fit is selected for clinical application. The posts are cemented or screwed inside the root canals along with dental cement and composite materials. At the time of cementing the post into the root space, the core is packed with dental composite material.
- Prefabricated posts: Materials:
- Metal alloys: titanium, base alloys, gold and silver: they are screwed inside the root space
- Fibre-reinforced composite resin posts: provide better resistance and aesthetics