Successful treatment of the avulsed tooth with immature root development is dependent on both pulpal and periodontal responses. The pulpal reaction is often one of revascularization with subsequent replacement of the necrotic pulp tissue. Continued root development and further calcification of the existing root structure are often seen with revitalization. The periodontal response to avulsion is dependent on the vitality of the periodontal ligament cells on the root surface. Normal healing occurs when the vitality is maintained, while replacement resorption results when the vitality is lost. Replantation after a short extra-alveolar period appears to provide the best prognosis for long-term retention of the avulsed tooth.