Post and core — what it is and when a crown needs one

Key facts

• A post retains the core; it does not strengthen the root
• Used only when too little tooth remains above the gum
• A healthy ferrule matters more than the post
• Fibre posts are tooth-coloured and more flexible
• Risks include root fracture and loosening

What is a post and core?

A post is a thin rod cemented a few millimetres into the cleaned root canal of a tooth that has already had root canal treatment. The core is a filling material built up around the top of the post to recreate the shape of a prepared tooth, onto which the crown is fitted. The purpose of the post is to retain the core when very little natural tooth is left above the gum, not to strengthen the root. This is a common misunderstanding. In fact, preparing a post space removes some root dentine, so posts are used only when the core would otherwise have nothing to hold on to.

When is a post needed, and when is it not?

A post is usually considered when more than half of the visible crown of the tooth is missing, typically after a large fracture or extensive decay in a front tooth or premolar. Molars have a large pulp chamber and several roots, so a bonded core often holds well without any post. A key factor is the 'ferrule': a band of healthy tooth, ideally one to two millimetres high, that the crown can hug around its base. A good ferrule matters more for long-term success than the post itself. If there is no ferrule and the tooth is very short, the dentist will discuss whether the tooth is restorable at all.

Fibre posts vs metal posts

Fibre posts are made of glass or quartz fibres in resin. They are tooth-coloured, bond to the tooth and flex more like natural dentine, which may reduce the risk of catastrophic root fractures and suits all-ceramic crowns on front teeth. Metal posts, either prefabricated or custom-cast, are very rigid and are sometimes chosen for heavily loaded teeth or unusual root shapes. Their drawbacks include possible grey shadowing through thin gums or ceramic and, if overloaded, a higher risk of root fracture that cannot be repaired. Dr. Manhal Helfawee chooses the post type according to the root, the remaining tooth and the crown material planned.

How a post and core is placed

First, the root canal filling is checked on an X-ray to confirm it is sound. Under local anaesthetic, part of the root filling is removed to create a space for the post, leaving a safe seal of root filling at the tip. The post is cemented or bonded, the core is built up around it and the tooth is shaped for a crown. A digital scan or impression is taken and a temporary crown is placed. At the next visit the final crown is fitted. The process is generally comfortable, similar to a filling, although some tenderness can follow for a day or two.

Risks and drawbacks of a post

Patients searching for the disadvantages of a dental post should know the main risks: root fracture, especially with rigid posts or heavy biting; perforation of the root during preparation, which is rare with careful technique; loosening of the post; and reinfection if the canal seal is disturbed or a temporary crown leaks. Removing an old post for retreatment can also be difficult. These risks are why posts are not used routinely. Seek a review promptly if a post-crown feels loose, if there is pain on biting, gum swelling or a pimple-like bump near the tooth, as these may indicate a crack or infection.

A crown covers and strengthens a damaged tooth; a bridge replaces a missing tooth by anchoring to the teeth on either side. Zirconia and porcelain options combine strength with a natural appearance.

Prepared by the Manhal Medical Center editorial team · Updated: 2026-10-18 · Treating specialist: Dr. Manhal Helfawee

This page is general information and does not replace a consultation. Suitability, risks and results vary between patients.