When a patient experiences pain due to decay, cracked, chipped, or traumatized teeth, a root canal may be necessary. Signs to look for include pain, prolonged sensitivity to cold or hot, discoloration of the tooth, and swelling or tenderness in the nearby gums. Sometimes there are no symptoms. Years ago when a patient had tooth pain, the dentist simply extracted the tooth and replaced it with a bridge or implant. Now, dentists realize that if they remove the infected nerve and seal it, the tooth can be saved. However, most of the time when a root canal is completed, a crown is necessary because the tooth can become brittle. If the root canal is not feasible, it will be necessary to extract the tooth and replace it with a bridge, implant, or removable prothesis.