1. Department of Periodontology, Operative and Preventive Dentistry, University Hospital Bonn, Welschnonnenstrasse 17, 53111 Bonn, Germany
2. Department of Prosthodontics, Preclinical Education and Dental Material Science, University Hospital Bonn, Welschnonnenstrasse 17, 53111 Bonn, Germany
3. Practice for Interdisciplinary Dentistry, Im Mühlenbach 2b, 53127 Bonn, Germany
4. Practice for Interdisciplinary Dentistry Dr. Menn, Dammstraße 4, 57271 Hilchenbach, Germany