Posts and Cores: What They Do and What They Do Not

What post and core involves

When a root-treated tooth has broken down to or below the gumline, there is nothing left above the gum for a crown to grip. A post solves that by extending down into the root canal: the canal filling is partly removed, a channel is prepared, and a post is cemented in. A core is then built around the part of the post that projects above the gum, and the crown is prepared on that. Two kinds exist. A cast post and core is made by the laboratory as one custom piece from an impression of the canal. A prefabricated post is a ready-made metal or fibre post cemented in at the chairside, with a bonded composite core built around it in the same visit — fewer appointments and lower cost.

When this treatment is used

Used on root-canal-treated teeth with insufficient remaining coronal structure to retain a crown. It is not needed on every root-treated tooth — most molars with intact walls do better without one.

Why a post is not automatically a good idea

A post does not strengthen a tooth. This is the single most common misunderstanding about them. Preparing the canal to receive one removes root dentine, and root fracture — which usually means losing the tooth — is the characteristic failure of post-retained restorations. The modern approach is therefore minimalist: use a post only when there is genuinely not enough coronal structure to retain the restoration otherwise, keep it as short and narrow as the retention requires, and preserve the apical seal. Fibre posts have gained ground partly because their flexibility is closer to dentine's, which may distribute stress more favourably than rigid metal.

Post removal, and why it is difficult

D2955 covers removing a post, which becomes necessary when a root-treated tooth needs retreatment or when the post itself has fractured. It is genuinely challenging work: the post is cemented into a narrow channel in a root, it has to come out without cracking the root, and the instruments involved apply significant force to a structure that cannot be replaced. Cast posts are harder to remove than prefabricated ones, and fibre posts are usually drilled out. Sometimes removal is not possible without unacceptable risk, and the honest alternatives become surgical treatment or extraction.

Costs and insurance in summary

Typical fee range across the group: $0–$0 where a single band applies. Several codes here are priced individually and carry their own range on their own page. Cast posts cost more than prefabricated ones because of the laboratory stage. Post removal is priced according to difficulty and can exceed placement.

Benefit category: Major, typically 50% on a typical plan. Covered as major restorative work when reported alongside a crown on a root-treated tooth. Claims for a post on a tooth with ample remaining structure are questioned.

Common restrictions: Usually requires the tooth to have had root canal treatment; Not normally payable together with a core build-up on the same tooth; Pre-authorisation commonly requested.