Endodontics also known as root canal therapy, involves the diagnosis, prevention, and treatment of oral pain and disease that originate from within the tooth. Root canal therapy involves the removal of diseased tissue, the repair of root structures, and the retreatment of teeth previously endodontically The dental pulp can become diseased and inflamed (most often indicated by temperature sensitivity or deep seated throbbing) and requires removal, hence a root canal procedure. In more advanced stages the dental pulp can necrose and become dead tissue. The tooth will no longer respond to temperature changes and sweets. The dead pulp tissue and bacteria from inside the tooth can affect the bone and cause infection outside the tooth at the root tip(s). These teeth hurt to bite on or become tender to touch. An x-ray will help in the diagnosis of this problem but only when the infection is so advanced as to cause loss of bone around the root tip of the tooth. Root canal therapy is the treatment of the inside of the tooth so that the source of infection/inflammation causing the dental pain can be removed.