Pins and Posts
Pins and posts are aids used to reinforce fillings and crowns when a large part of the tooth is decayed or missing. Both pins and posts can be used in the same tooth, if necessary. Each situation is different. Your dentist will decide on a case-by-case basis if you need pins or posts.
Pins are thin shafts of metal that are either cemented or screwed into the tooth. They provide anchors for a filling or crown. Your dentist drills small holes in the tooth and places the pins. Then the filling is built around the pins or the crown is placed over them. There are several types of pins, including threaded, friction and roughened pins.
Today, with advances in adhesive dentistry, we have newer materials that create both mechanical and chemical bonds to the tooth. For this reason, pins are used much less often. The bonds help to keep the filling in place. In many cases, this eliminates the need for a pin. The shape of the tooth affects whether a pin is needed. So does the amount of force placed on the tooth when you bite. Pins do increase the risk of damaging the tooth by potentially creating small cracks in the tooth.
Posts are thicker shafts of metal or composite materials used in teeth that have had root-canal treatment. In root canal treatment, the dentist removes the tooth's pulp. This is the part of the tooth that contains nerves and blood vessels. This leaves a void in the tooth. A post is placed through the center of the tooth, where the pulp used to be. It provides an anchor for a crown. Posts are either bonded or cemented in place. They can be prefabricated or made just for you.
There are many different types of prefabricated post systems. They include parallel sided, tapered, threaded and serrated posts made of metals such as titanium or stainless steel. They can also be made of a composite fiber that causes less potential for cracking the root.
Prefabricated posts are placed in one visit and cemented in place. They are less expensive than a post and core made in a laboratory. The post serves as the anchor for a buildup of "core" material, which eventually will hold your crown. However, the core material that is attached to the post is often made of composite or plastic material, glass ionomer or amalgam. This material can break or fail. As an alternative, your dentist can have a one-piece post and core made in a laboratory (cast).
A cast post and core is made from an impression of the tooth that your dentist will take after completing the root canal and preparing the tooth. This method is especially useful when minimal tooth structure is present. Because a cast post and core is all one piece, it is stronger than a prefabricated post. Also, it is cemented in place. It does not stay in place using friction, as is often the case with prefabricated posts. A cast post and core is less likely than a prefabricated post to fracture your root. It does cost more than a prefabricated post and core, because of the extra time and materials needed. Cast post and cores also can be less likely to stay in place than the prefabricated kind, because they are held only by cement. However, cast posts and cores do not usually come loose.
Once the post and core is placed, the dentist will prepare your tooth for a crown. Regardless of which type of post system is used, having adequate tooth structure for the crown to hold onto is key for the retention of the restoration.
Updated- January 22, 2021
References:
- Marchionatti AME, Wandscher VF, Rippe MP, Kaizer OB, Valandro LF. Clinical performance and failure modes of pulpless teeth restored with posts: a systematic review. Braz Oral Res. 2017 Jul 3;31:e64. doi: 10.1590/1807-3107BOR-2017.vol31.0064. PMID: 28678974.
- Raedel M, Fiedler C, Jacoby S, Boening KW. Survival of teeth treated with cast post and cores: A retrospective analysis over an observation period of up to 19.5 years. J Prosthet Dent. 2015 Jul;114(1):40-5. doi: 10.1016/j.prosdent.2014.08.017. Epub 2015 Apr 7. PMID: 25862272.
- Reis JMDSN, Oliveira CRM, Reis EGJ, Mascaro BA, Abi-Rached FO. One-step fiber post cementation and core build-up in endodontically treated tooth: A clinical case report. J Esthet Restor Dent. 2020 Jan;32(1):5-11. doi: 10.1111/jerd.12551. Epub 2019 Nov 23. PMID: 31758748.