Properly performed, a root canal is no more uncomfortable than having a cavity filled, though the procedure is more complex. It is the removal of infected or dead pulp (the inner nerves and blood vessels) from inside the tooth, and the filling and sealing of the resulting space.
An infected (abscessed) tooth causes discomfort in the form of swelling and toothache. It can also cause severe health complications, because the bacteria from the infection can enter the bloodstream and travel to other parts of the body.
One way to treat the infection is to remove the tooth and disinfect the area. However, tooth loss creates a gap between surrounding teeth that often necessitates a dental implant or bridge. It is preferable to save the tooth if possible through root canal (endodontic) treatment.
The dentist begins by applying local anesthesia and isolating the area with a rubber dam. Then they drill an opening in the tooth to access the infected pulp, and remove it and clean the area with specialized tools. The dentist fills the root space with a filling material. Finally the dentist must seal the surface of the tooth with a crown to prevent further infection and restore the function and appearance of the tooth.
The root canal treatment is typically performed in one visit. A second visit may be required to complete the crown restoration.