Once a cavity is deep into the tooth it has caused pain, is causing pain or will cause pain. Root canal therapy allows you to keep your tooth as we remove the infected pulp tissue from the innermost part of the tooth. Removing this tissue helps relieve pain and saves the tooth. Root canal therapy is a great way to relieve pain. At Marley Park Family Dentistry, most patients are so comfortable during a root canal they are able to catch up on some sleep.