1. Department of Oral and Maxillofacial Diseases, Head and Neck Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
2. Institute for Molecular Medicine (FIMM), Helsinki, Finland.
3. Department of Health, National Institute for Health and Welfare, Helsinki, Finland.
4. Department of Public Health, Clinicum, University of Helsinki.
5. Division of Periodontology, Dentognostics GmbH, Jena, Germany.
6. Department of Dental Medicine, Karolinska Institute, Huddinge, Sweden.