1. School of Health and Society; Department of Oral Health Sciences; Kristianstad University; Kristianstad Sweden
2. School of Dental Science; Trinity College; Dublin Ireland
3. Blekinge Institute of Technology; Karlskrona Sweden
4. Departments of Periodontics and Oral Medicine; School of Dentistry; University of Washington; Seattle WA USA
5. School of Dentistry; Section of Periodontics; University of California, Los Angeles; Los Angeles CA USA