1. Division of Periodontology; Department of Dental Medicine; Karolinska Institutet; Huddinge Sweden
2. Department of Oral Diagnostics; Malmö University; Faculty of Odontology; Malmö Sweden
3. Department of Periodontology; Malmö University; Faculty of Odontology; Malmö Sweden
4. Department of Oral and Maxillofacial Diseases; University of Helsinki; Helsinki University Central Hospital; Helsinki Finland