A post and core is a foundational dental restoration used to rebuild a tooth that has lost a significant amount of its original structure, often following extensive decay or fracture. This two-part system is necessary when the remaining tooth material is too minimal to support a traditional crown on its own. The procedure acts as an internal anchor, creating a stable platform to which a final crown can be securely attached. By placing a post and core, dentists can effectively save a compromised tooth that might otherwise require extraction, thereby preserving the patient’s natural bite and dental arch.
The Need for Structural Support
A tooth that has undergone root canal therapy frequently requires internal reinforcement. This is because the procedure involves removing the inner pulp chamber, which weakens the overall structure and leaves the tooth walls thin. When less than half of the tooth structure remains, a post and core becomes necessary to ensure the long-term success of the final restoration.
The primary function of the post and core is not to strengthen the root itself, but to provide retention and resistance form for the crown that will eventually cover the tooth. Retention refers to the ability to hold the crown in place against vertical forces, such as biting, that try to pull it off. Resistance form prevents the crown from being dislodged by lateral or rotational forces, like those encountered during chewing. The post anchors into the solid part of the root, and the core builds up the missing coronal portion, creating the ideal shape for the crown to seat properly.
Components and Materials Used
The system is composed of two distinct parts: the post and the core. The post is a small, rod-like structure inserted deep into the root canal space and secured with dental cement. The core is the restorative material built up around the exposed portion of the post, which replaces the missing tooth structure and is sculpted to the precise shape of a prepared tooth ready for a crown.
Posts are made from several different materials, including metal or fiber. Traditional metal posts, which can be prefabricated or custom-cast, offer high rigidity and strength, often made from titanium or stainless steel alloys. Fiber posts, composed of glass or quartz fibers embedded in a resin matrix, have become common. These fiber posts are favored because their flexibility, or modulus of elasticity, more closely resembles that of natural dentin, which helps distribute stress more evenly and reduce the risk of root fracture. The core material is a resin-based composite or dental amalgam, chosen for its ability to be bonded securely and shaped precisely.
The Placement Procedure
The post and core procedure begins after the tooth has been successfully treated with a root canal. The dentist first prepares the root canal space by carefully removing a portion of the filling material, or gutta-percha, to create the correct depth and diameter for the post. A specific length of the root canal filling material must remain at the apex to maintain the seal and prevent future infection.
Once the post space is prepared, the chosen post is seated into the canal using a specialized dental cement or bonding agent. If a custom-cast metal post is required, an impression of the prepared canal is taken and sent to a lab for fabrication, necessitating a second appointment for placement. After the post is secured, the core material is layered and molded around the exposed head of the post. This core buildup is then shaped to the exact specifications required for the final crown before the permanent crown is placed to complete the restoration.
Longevity and Follow-Up Care
The expected lifespan of a post and core is closely tied to the success of the final crown placed over it. Regular oral hygiene and professional dental checkups are fundamental to ensuring the longevity of the treated tooth. The tooth, even with the post and core, is not indestructible and requires the same care as natural teeth to prevent recurrent decay at the margins of the crown.
The potential for a root fracture is a risk specific to this procedure, which can occur if the post is too rigid or if excessive force is applied during chewing. Fiber posts are preferred because their biomechanical properties mitigate this risk by acting as a shock absorber. Any sign of discomfort, swelling, or pain years after the procedure should be promptly evaluated, as a complication could require a new restoration or, in severe cases, extraction. Ultimately, the post and core provides the necessary foundation, but the integrity of the surrounding natural root and the quality of the final crown determine the tooth’s long-term fate.