When you undergo a root canal or other endodontic treatment, the inflamed or infected pulp is removed and the inside of the tooth is carefully cleaned and disinfected, then filled and sealed with a rubber-like material called gutta-percha. First, an opening is made through the back of a front tooth or the crown of a molar or pre-molar. After the diseased pulp is removed (a pulpectomy), the pulp chamber and root canals are cleaned, enlarged and shaped in preparation for being filled. When people are told that they need a root canal treatment, they usually think about pain. However, the pain they feel is caused by an infection in the tooth, not by root canal treatment. ... The root canal procedure itself is painless. A local anesthetic numbs the tooth and the surrounding area.