1. Periodontitis, professor and chairman, University of Ghent, Faculty of Medicine and Health Sciences, Dental School, Department of Periodontology and Oral Implantology, Ghent Belgium;
2. student undergraduate dentistry, University of Ghent, Faculty of Medicine and Health Sciences, Dental School Department of Periodontology and Oral Implantology, Ghent, Belgium;
3. periodontist, Centre for Periodontology and Oral Implantology, Heverlee, Belgium;
4. maxillofacial surgeon, professor and chairman, AZ Sint‐Jan, Department of Oral and Maxillofacial Surgery, Bruges, Belgium;
5. periodontist, professor, University of Berne, Department of Periodontology, Division of Oral Microbiology, Berne, Switzerland; and periodontist, professor, University of Washington, Department of Periodontics, Seattle, WA, USA;
6. professor, Free University of Brussel (VUB), Dental Medicine, Brussels, Belgium, and assistant professor, University of Ghent, Faculty of Medicine and Health Sciences, Dental School, Department of Periodontology and Oral Implantology, Ghent, Belgium