Core Build-Ups, Posts and Cores
Whenever a tooth has lost significant coronal tooth structure (the part of the tooth above your gum) due to tooth decay, fractures and root canal treatment, it becomes weak and if not properly strengthened can be lost. This is when the dentist will decide, based on the specific situation, whether a core build-up or a post and core is appropriate. Core build-ups are done more frequently than posts and cores. As a general rule, if more than half the coronal tooth structure is lost, then we need to posts and cores. If less than half the coronal tooth structure is lost, we do core build-ups. Core build-ups are therefore an addition to the remaining coronal tooth structure. They can be made with composite resins or silver amalgams. However, more and more dentists today are choosing to do the core build-ups with composites as there is better bonding ability with the composite resins. Once the core build-up (composite resin filling material) is bonded to the tooth, it becomes a part of the tooth, and then the tooth is prepared to receive a crown.
Core build-ups accomplish three goals. They give strength, retention, and protect the pulp (nerve of tooth) underneath the crown. Posts and cores are done after the tooth has had a root canal treatment. Root canal treatment takes away the nerve and the blood supply from the tooth, causing the tooth to lose its vitality, making the tooth more prone for fracture. As mentioned before, when more than half the coronal tooth structure is lost, there is not enough tooth left to bond to a filling material (or to do a core build-up). During those situations, we do posts and cores. To do posts and cores we need to remove some of the root canal filling material to make room for the post. Posts are made of metal or carbon fiber, which are inserted into the root of the tooth and extend into the coronal tooth structure. The purpose of the post is to anchor the remaining tooth to the filling material, which is bonded to the tooth. The post maintains the integrity of the tooth by connecting the tooth to the filling material. Not all root canal treated teeth need posts, although most do. Once the post and core is done, the tooth should have a crown. Read about crowns for more information. If you still have questions, you are welcome to call the office.