1. Department of Oral and Maxillofacial Surgery, University of Erlangen-Nuremberg, Erlangen, Germany.
2. Department of Oral and Maxillofacial Surgery, Kantonsspital Lucerne, Switzerland.
3. University of Erlangen-Nuremberg, Erlangen, Germany
4. Department of Phoniatrics and Pedaudiology, University of Erlangen-Nuremberg, Erlangen, Germany.
5. Department of Oral and Maxillofacial Surgery, University of Athens, Athens, Greece.
6. Department of Otorhinolaryngology, University of Erlangen-Nuremberg, Erlangen, Germany