1. Laboratory of Hygiene, Social & Preventive Medicine and Medical Statistics, Department of Medicine, School of Health Sciences, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece
2. Department of Oral and Maxillofacial Surgery, University Hospital of Crete, 715 00 Heraklion, Greece
3. Department of Oral and Maxillofacial Surgery, George Papanikolaou General Hospital, 570 10 Thessaloniki, Greece
4. Consultant Hepato-Pancreato-Biliary Surgeon Honorary Lecturer, Division of Surgery & Interventional Science, University College London, London NW3 2PS, UK
5. School of Medicine and School of Law, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece
6. Department of Oral and Maxillofacial Surgery, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece