A post and core is a restorative dental procedure used to rebuild a severely compromised tooth, providing a stable foundation for a final dental crown. This two-part system is typically required when a tooth has lost most of its natural structure, usually after a root canal treatment. The post is a small, rod-like anchor inserted deep into the tooth’s root. The core is a material built up around this post to replace the missing coronal tooth structure. This creates an artificial base that allows a permanent restoration to be securely placed, salvaging the tooth.
When Dental Structure Requires Reinforcement
A post and core is necessary when the remaining tooth structure above the gum line is insufficient to hold a standard dental crown. This often results from extensive decay, a significant fracture, or the material removal required during root canal therapy. If more than half of the tooth’s original coronal structure is missing, a standard crown lacks the necessary surface area for mechanical retention and cannot withstand chewing forces without internal support.
The decision to use a post and core depends on the amount of remaining sound tooth tissue, known as the ferrule. Dentists aim to preserve at least 1.5 to 2 millimeters of healthy tooth structure circumferentially. This ensures the restoration’s success and helps prevent root fracture. Without this minimal ferrule, biting forces transfer directly to the root, increasing the risk of long-term failure. The post secures the core material, which ultimately supports the crown, but does not strengthen the overall tooth.
The Post and Core Placement Procedure
Placement begins only after the root canal treatment has been successfully completed and sealed. The dentist uses specialized drills, such as Peeso reamers or Gates-Glidden drills, to carefully remove a portion of the root canal filling material (gutta-percha) from the coronal section of the root. This creates a precisely measured space, known as the post space, within the canal. A minimum of 4 to 5 millimeters of the root canal filling must remain at the tip of the root to maintain the apical seal and prevent contamination.
Once the space is prepared, a trial post is selected and fitted to ensure it extends deep enough into the root for optimal retention. The post is then cemented into the canal using a specific luting agent or bonding system. After the post is secured, the core material is built up around the protruding post and the remaining natural tooth structure. This core build-up is sculpted to recreate the anatomical shape of the missing structure. The final step involves shaping the core material to the precise dimensions required to seat the permanent dental crown.
Different Materials Used for Posts and Cores
The materials chosen for the post and core vary based on the tooth’s location, remaining structure, and aesthetic requirements. Posts are categorized into metal and non-metal options, each having distinct mechanical properties.
Metal Posts
Metal posts, such as stainless steel, titanium, or gold alloy, offer high rigidity and strength. They are a suitable choice for posterior teeth that endure heavy biting forces. However, their opaque nature can compromise the final appearance of an all-ceramic crown, especially in the front of the mouth.
Non-Metal Posts and Core Material
Non-metal posts, such as fiber-reinforced composite (fiberglass) or ceramic (zirconia) posts, are favored for their aesthetic qualities and flexibility. Fiber posts have an elasticity closer to natural dentin, allowing them to flex slightly under stress. This potentially reduces the risk of root fracture compared to rigid metal posts. The core material is typically a composite resin, which is tooth-colored and bonds well to the post and remaining tooth structure. While traditional materials like dental amalgam may occasionally be used for durability, tooth-colored composite is now the standard.
Securing the Final Crown Restoration
The function of the post and core system is to act as a stable, unified unit that provides retention for the permanent dental crown. Once the core material is shaped, it mimics a prepared tooth, giving the crown a solid foundation for cementation. The crown is designed to fit over the core and extend slightly past the core-tooth junction. This creates a collar of material that encircles the tooth, known as the ferrule effect. This crown margin protects the underlying tooth and the post-core complex from recurrent decay and external forces.
This final restoration provides the necessary strength and structural integrity for the tooth to return to full function, allowing for normal chewing and biting. A well-executed post and core, followed by a properly seated crown, can have an expected lifespan ranging from 5 to over 15 years. Maintaining excellent oral hygiene and attending routine dental check-ups are important factors in ensuring the long-term success and longevity of the entire restoration.