1. Department of Oral & Maxillofacial Surgery, Helios Hospitals, 34121 Kassel, Germany
2. Deptartment of Oral & Maxillofacial Surgery, University of Groningen, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands
3. Oral and Maxillofacial Surgeon, Umeå University, 901 87 Umeå, Sweden
4. Department of Oral and Maxillofacial Surgery, Aalborg University Hospital, 9000 Aalborg, Denmark
5. Emeritus Consultant Oral and Maxillofacial Surgeon, Mersey Regional Health Authority, UK