When you have a tooth that has encountered moderate damage in the nerve that causes pain and sensitivity but the tooth is still intact, your dentist may recommend undergoing root canal therapy. You might not want to have a root canal therapy because you’re afraid that root canal will be painful. But more than this being a painful procedure, this will help treat the pain and sensitivity of your tooth. This treatment removes the badly damaged inside part of the tooth called pulp where the nerves are located as well as saves your tooth by cleaning and sealing the space with a sealant or filling. But if this procedure really saves the teeth and even promises to last a lifetime, why do some people get root canal infection years later?