If a tooth becomes cracked or extensively decayed, bacteria can enter the pulp tissue and germs can cause an infection or severe inflammation inside the tooth. If untreated, an abscess will form, resulting in pain and swelling. During root canal treatment, the dentist removes the affected tissue, cleans and shape the canals, and fills them with a material that is biologically safe for the tooth. The tooth is filled with a composite material and a crown is placed.

While they have a bad reputation, root canals are now painless with effective anesthetics.