1. Department of Otorhinolaryngology; University Medical Centre of the Johannes Gutenberg-University Mainz; Mainz Germany
2. Department of Oral, Maxillofacial and Plastic Surgery; University Medical Centre Rostock; Schillingallee 35 18057 Rostock Germany
3. Department of Oral, Maxillofacial and Plastic Surgery; Federal Armed Forces Hospital Koblenz; Germany
4. Department of Oral, Maxillofacial and Plastic Surgery; University Medical Centre Halle (Saale); Germany