1. Department of Health; Department of Oral Surgery and Policlinical Ambulance; Faculty of Dental Medicine; University of Witten/Herdecke; Witten Germany
2. Department of Health; Department of Operative and Preventive Dentistry; Faculty of Dental Medicine; University of Witten/Herdecke; Witten Germany
3. Department I: Epidemiology and Delivery of Health Care Services; Institute of German Dentists; Cologne Germany
4. Private Practice; Deggendorf Germany
5. Faculty of Dental Medicine; Department of Oral Surgery and Policlinical Ambulance; University of Witten/Herdecke; Witten Germany