The goal of orthodontic therapy is to achieve a functional and aesthetically correct occlusion, while observing the face as a whole. The basis of the orthodontic movement lies in the process of remodeling the supporting tissue of a tooth, therefore the health of the periodontium can be used as an assessment of the therapy outcomes. Although many studies have shown that orthodontic movement can have a positive effect on the periodontium’s health, there is also evidence indicating that periodontal complications are the most common side effects of orthodontic therapy. They mostly occur if the orthodontist applies too much force, or the patient does not maintain oral hygiene. The most common complications are hyperplasia, ingrowth, recessions, and loss of the interdental papilla, resulting in the formation of black triangles between the teeth. Likewise, gingivitis, periodontitis, resorption of the alveolar bone and pocket may occur, which endangers the tooth and leads to its desensitization. For the therapy to be successful among the patients with healthy periodontium or periodontal complications, good cooperation between those two specialist branches is extremely important. That is the only way to ensure a successful therapy outcome, a favorable prognosis for the teeth and the periodontal system, and minimal occurrence of complications and patient dissatisfaction.