Many tooth problems involve infections that spread to the pulp, which is the inner chamber of the tooth containing blood vessels, nerves, and other tissues. When the infection becomes worse, it can begin affecting the roots. Root canal therapy involves removing the diseased tissue, halting the spread of infection, and restoring the healthy portion of the tooth. In fact, root canal therapy is designed to save a problem tooth. Most patients who have  root canal experience little or no discomfort or pain, and enjoy a restored tooth that can last almost as long as its healthy original.