A root canal is necessary when and untreated deep cavity infects the blood and nerve supply of a tooth.

As a result of this deep infection the tooth may become severely painful. Depending on the severity of infection root canals may require one to two visits not including any follow-up visits.

To treat the infected nerve the dentist must first gain access to the inside of the tooth removing all the decay. Then each tiny canal inside the root system must be identified and cleaned out of its infected tissues using small tapered instruments called files. Once the hand filing of the canals is completed the canals are further prepared using rotary instruments that open up the canals to a precise taper and length.

The canals are then each filled with an inert flexible plastic material called gutta percha that seals off the canals from any further bacterial invasion.

To add structural stability to the tooth the canal spaces may be further prepared to allow for the placement of reinforcing posts in the tooth. The posts are now placed in the prepared space; finally a dense filling material is injected into the tooth cavity.

The core filling is then packed and shaped to resemble the bite surface of the tooth and cured to hardness with a specialized blue light source.

To minimize the chances of breakage or fracture it is highly recommended that a crown be placed on the tooth, the crown is usually placed as soon as possible.