In the last years, a significant development has taken place in the orthodontic treatment of adult Patients. Adult orthodontics is different than that for children because in adults there is virtual no more growth and because there are changes in the tooth supporting structures: the periodontium. The orthodontic treatment is carried out through the medium of periodontium so a healthy tooth supporting system is the essential prerequisite for carrying out the orthodontic treatment. At the same time, as the tooth is moving under the effect of orthodontic force, various changes occur in the periodontium under the effect of force. So, it is important that the orthodontic treatment is periodontally compromised patient be considered separately as they are more prone to further bone loss; the reduced periodontium cannot sustain further loss without the potential loss of teeth. The reduced periodontal support dictates altered treatment design, mechanics and retention. At the same time it is important to consider the limits of periodontium while carrying out orthodontic treatment so that there is no damage due to inadvertent intervention.