1. Unit of Periodontology; Department of Restorative Dentistry; Periodontology and Endodontology; University Medicine; Ernst-Moritz-Arndt-University Greifswald; Greifswald Germany
2. Department of Epidemiology; Mailman School of Public Health; Columbia University; New York NY USA
3. Section of Oral and Diagnostic Sciences; Division of Periodontics; Columbia University College of Dental Medicine; New York NY USA
4. Department of Prosthodontics; Gerodontology, and Biomaterials; University Medicine; Ernst-Moritz-Arndt-University Greifswald; Greifswald Germany
5. Institut National de la Santé et de la Recherche Médicale; Unité Paris France
6. École des Hautes Études en Santé Publique; Paris et Rennes France