A post and core crown is a type of dental restoration required where there is an inadequate amount of sound tooth tissue remaining to retain a conventional crown. A post is cemented into a prepared root canal, which retains a core restoration, which retains the final crown.
The role of the post is firstly to retain a core restoration and crown, and secondly to redistribute stresses down onto the root, thereby reducing the risk of coronal fracture. The post does not play any role in reinforcing or supporting the tooth and can in fact make it more likely to fracture at the root.
When deciding whether or not a tooth requires a post and core crown rather than a conventional crown, the following must be established:
- Presence of an adequate ferrule(coronal tooth structure)
- Sufficient length of canal to retain a post
- Curvature and overall anatomy of root canal system
- Sufficient root (radicular) dentine thickness for post preparation
- Restorability of tooth
The purpose of this article is to identify and describe the newer materials and techniques deemed as viable alternatives to metallic post/cores, and to propose a rationale for the selection of one product or restorative technique protocol over others for simple and complex postendodontic restorations. These are indicated where remaining coronal tooth structure is less than 50% and/or the core strength is compromised by the endodontic access opening.
Traditionally metal posts have been used due to the good corrosion resistance and high yield strength.
Prefabricated metal posts
Stainless steel, titanium, titanium alloy and gold alloy are used to construct prefabricated posts. These type of posts are usually placed in the post space and the core is constructed with a direct restorative core material.
There are also prefabricated posts for which cores are cast onto. These posts are usually made of Type IV gold alloy (containing gold, platinum, palladium and iridium) or platinum, gold and iridium alloys, which are compatible with palladium and silver-free alloys or platinum, gold, palladium and silver alloy