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