Harmonious cooperation of the general dentist, the periodontist and the orthodontist offers great possibilities for the treatment of combined orthodontic–periodontal problems. Orthodontic treatment along with patient’s compliance and absence of periodontal inflammation can provide satisfactory results without causing irreversible damage to periodontal tissues.Orthodontic treatment carries with it the risks of tissue damage, treatment failure and an increased predisposition to dental disorders. The dentist must be aware of these risks in order to help the patient make a fully informed choice whether to proceed with orthodontic treatment. The aim of this study is to discuss the principles of orthodontic treatment in patients with reduced periodontium, its indications and limitations, as well as current views concerning retention of orthodontic result.