1. Department of Oral & Maxillofacial Surgery; Red Cross Hospital; Kassel Germany
2. Clinic of Cranio-Maxillofacial and Oral Surgery; University of Zürich; Zürich Switzerland
3. Faculty of Odontology; University Complutense of Madrid; Madrid Spain
4. Institute of Physiological Chemistry; Dresden University of Technology; Dresden Germany
5. Department of Periodontology; University Gießen and Marburg; Giessen Germany