1. Department of Periodontology U.F.R. of Odontology Université de Paris Paris France
2. Department of Periodontology Service d'Odontologie AP‐HP Rothschild Hospital Paris France
3. Inserm Population‐based Epidemiologic Cohorts Unit, UMS 011 Villejuif France
4. Private Practice Hamburg Germany
5. Department of Operative Dentistry and Periodontology Faculty of Medicine University of Freiburg Freiburg Germany
6. Department of Periodontology School of Dental Medicine University of Bern Switzerland
7. EA 2496 U.F.R. of Odontology University of Paris Paris France