During 200 years of progress in endodontics, various sciences have contributed to our understanding of the physiology and pathology of the dental pulp. Early treatment included cauterization of the pulp, the use of poultices or leeches, and tooth transplantation or replantation. Various methods of pulp devitalization are reviewed. Near the turn of the century, the discovery of X rays made diagnosis more accurate and the discovery of local anesthetics eliminated pain during endodontic treatment. Although the focal infection theory slowed the acceptance of endodontic treatment in this century, the biomechanical concept of treatment and research have recently opened new avenues for treatment and have initiated improvements in medicaments and filling materials.