1. Unit of Periodontology; Department of Restorative Dentistry, Periodontology, and Endodontology; University Medicine; Ernst-Moritz-Arndt-University Greifswald; Greifswald Germany
2. Department of Prosthodontics, Gerodontology, and Biomaterials; Centre of Oral Health; Greifswald University; Greifswald Germany
3. Department of Periodontology; Medical Faculty Carl Gustav Carus; Dresden Germany
4. Institute for Community Medicine; University Medicine of Greifswald; Greifswald Germany
5. Institute of German Dentists; Köln Germany