1. Department of Periodontology, Dental Clinic, Faculty of Medicine Sigmund Freud University Vienna Austria
2. Department of Periodontology, Faculty of Odontology University of Malmö Malmö Sweden
3. Department of Epidemiology and Public Health University College London London UK
4. Department of Orthodontics and Dentofacial Orthopedics, School of Dental Medicine University of Bern Bern Switzerland
5. Department of Odontology, Section of Molecular Periodontology Umeå University Umeå Sweden
6. Gastrounit, Medical Division Copenhagen University Hospital ‐ Amager and Hvidovre Hvidovre Denmark
7. Copenhagen Center for Inflammatory Bowel Disease in Children, Adolescents and Adults Copenhagen University Hospital ‐ Amager and Hvidovre Hvidovre Denmark
8. Division of Conservative Dentistry and Periodontology University Clinic of Dentistry, Medical University of Vienna Vienna Austria