"Endodontics encompasses the study (practice) of the basic and clinical sciences of normal dental pulp, the etiology, diagnosis, prevention, and treatment of diseases and injuries of the dental pulp along with associated periradicular conditions. In clinical terms, endodontics involves either preserving part, or all of the dental pulp in health, or removing all of the pulp in irreversible disease. This includes teeth with irreversibly inflamed and infected pulpal tissue. Not only does endodontics involve treatment when a dental pulp is present, but also includes preserving teeth which have failed to respond to non-surgical endodontic treatment, or for teeth that have developed new lesions, e.g., when root canal re-treatment is required, or periradicular surgery. Root canal treatment is a dental procedure used to treat infected tooth pulp which would be otherwise extracted. The pulp is the soft tissue core of the tooth which contains nerves, blood supply and connective tissue necessary for tooth health.[4] This is usually caused when bacteria enter the pulp through a deep cavity or failed filling."