Why do I need a post and a crown after a root canal?

Q. Why do I need a post and crown after a root canal?

A. When a tooth has a root canal, an access hole is made in the top of the tooth and the pulp of the tooth is removed – including any infection or inflamed pulpal tissue.  In addition to removing the nerve, this also hollows out the tooth, compromising the structural integrity of the tooth.  For this reason, the root canal treated tooth is much more prone to fracture.  By placing a crown (a tooth-shaped cap) on the tooth, the cusps are tied together and are much less likely to fracture in the future.

Additionally, when a root canal is indicated, it is often because decay or a crack in the tooth has reached the pulp of the tooth and caused irreversible damage to the nerve of the tooth.  Because of this, there is usually a significant amount of damaged tooth structure when the root canal is performed.  This is an additional reason that a crown is necessary in order to restore the tooth.

A post is not always necessary. However, if a significant amount of the tooth is missing, a post and a ‘core’ of filling material may be necessary to support the crown.  Posts can be made of metal or fiber-reinforced resin and are cemented in the canal space of the tooth to aid in replacing the missing tooth structure.

There are some cases when a root canal is needed when most of the tooth structure is able to be preserved.  Even in this case, a crown is usually recommended due to the increased likelihood of cusp fracture.

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