Orthodontic treatment aims at providing acceptable functional and aesthetic occlusions using appropriate tooth movements. These movements are specifically related to interactions of the teeth with their supportive periodontal tissues. Periodontic and orthodontic interactions usually deal with the establishment of an appropriate diagnosis and the treatment planning needed to enable coordinated periodontic-orthodontic therapy. A harmonious cooperation of the periodontist and the orthodontist offers great possibilities for the treatment of various orthodontic-periodontal problems. The present discussion focused on the effects of a combined periodontal and orthodontic treatment on the periodontal health and dentofacial aesthetics, and the mode that each field can contribute to optimize treatment of combined orthodontic-periodontal clinical problems.