There is an increasing number of patients with insuffixient periodontal tissue in orthodontic therapy. The most common reason for their inclusion in orthodontic therapy is aesthetic. Orthodontists dealing with such a therapy face many challenges. The aim of such therapy is to obtain a satisfactory aesthetic result while preserving the health of the periodontal. Orthodontic moves in such patients should be conducted with lightly interrupted forces. Before, during and after orthodontic therapy, periodontal therapy is necessary. It is also important to educate and motivate the patient to maintain a good oral hygiene. If either the orthodontist or the patient does not comply, if the orthodontist applied too strong orthodontic forces or the patient does not maintain good oral hygiene, negative changes may occur on the soft and hard tissue of the periodontal. The most common amongst them are hyperplasia, the invagination and recession of gingiva, the loss of interdental papilla and consequently the creation of "black triangles". It may also result in deepening of periodontal pockets, alveolar bone resorption and root resorption, which together can lead to dental destabilization and the possibility of tooth loss. A very good co-operation between periodontologists and orthodontists is needed to make the therapy of such patients successful and to minimize negative changes. Only this allows a successful outcome of therapy, a long-term good prognosis and minimal occurrence of complications.