Between orthodontics and periodontology there are many correlations, especially in the treatment of adults with already-damaged periodontal tissues and malocclusions. Aim of this paper was to emphasize that an interdisciplinary periodontal-orthodontic treatment could be beneficial even in a case that seemed hopelessly. A typical case of an adult patient with extensive bone loss due to periodontal disease, occlusal trauma caused by dental malpositions, spacing due to early loss of teeth in the lateral segments and pathologic tooth migration will be presented. The orthodontic treatment was initiated at 3 months after the stabilization of the periodontal therapy and was done with a fixed appliance. During the orthodontic stage periodontal maintenance visits continued at 2-month intervals. The therapy of"black triangles" occurred due to the loss of interdental gingiva was done by stripping followed by a space-closure procedure. A permanent retainer was applied. Benefits and problems of the comprehensive periodontal-orthodontic therapy and treatment protocols will be presented. In conclusion the interdisciplinary therapy of this patient, with a good compliance, was beneficial, improved esthetics, the periodontal status, the ability of the patient to clean the teeth and also led to best position of the abutments for optimal placement of prosthetic reconstructions.