1. Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin; Humboldt-Universität zu Berlin, and Berlin Institute of Health; Department of Prosthodontics; Geriatric Dentistry and Craniomandibular Disorders; Berlin Germany
2. Medical Center - University of Freiburg, Center for Dental Medicine; Department of Prosthetic Dentistry; Faculty of Medicine - University of Freiburg; Freiburg Germany
3. Medical Center - University of Freiburg; Center for Medical Biometry and Medical Informatics; Institute for Medical Biometry and Statistics; Faculty of Medicine - University of Freiburg; Freiburg Germany