First, a small opening is made on the crown to remove the infected pulp. Since this is done under local anesthesia, the treatment is completely painless. After cleaning the root canal the dentist enlarges it with special files, so it can be easily filled.
In case the root canal treatment is carried out over multiple sessions, the dentist may place medication in the cleaned canal to kill any remaining bacteria and seals the tooth with a temporary filling.
During the following visit, the medication and the temporary filling is removed, and the root canal filling is placed. Finally, the dentist seals the tooth with a filling or a crown, depending on the extent of the damage.