Periodontal health is essential for any form of dental treatment. Adult patients must undergo regular oral hygiene instruction and periodontal maintenance in order to maintain healthy gingival tissue during active orthodontic treatment. Close monitoring of adults with reduced periodontal support is mandatory. Adult orthodontic tooth movement can be performed on both healthy and diseased periodontia with few detrimental effects (root resorption) provided physiologic forces are used, periodontal inflammation is controlled and meticulous oral hygiene is maintained throughout active therapy. With this basic understanding of periodontic orthodontic interrelationships, the clinician can then work accordingly in the patient's best interest. However, the combined therapies are founded in repeated clinical Successes that have provided patients with pleasing aesthetics, healthy function and increased longevity of their natural dentitions. Patients will continue to benefit from the combination of research and shared clinical information that the specialties of Orthodontics and Periodontics will provide.