When the pulp of a tooth becomes infected or dies, root canal therapy is necessary to save the tooth. It is generally comfortable treatment that can save your tooth and keep your mouth healthy. You may realize that you have an infected tooth when: the tooth is sensitive to hot or cold, the tooth hurts with biting or pressure, there is throbbing severe tooth pain, the area is swollen, or you have a bad taste in your mouth. You may also be unaware of the problem because there are no symptoms at all. It is important to treat an infected tooth in order to prevent the infection from spreading through the root tips and causing a painful abscess in the jawbone.