1. Department of Periodontology, Institute of Dentistry University of Turku Turku Finland
2. Department of Periodontology, Faculty of Dentistry Biruni University Istanbul Turkey
3. Department of Oral and Maxillofacial Diseases, Head and Neck Center University of Helsinki and Helsinki University Hospital Helsinki Finland
4. Division of Periodontology, Department of Dental Medicine Karolinska Institutet Stockholm Sweden
5. Department of Periodontology, Faculty of Dentistry Bezmialem Vakif University Istanbul Turkey
6. Department of Community Dentistry, Institute of Dentistry University of Turku Turku Finland