1. Department of Oral and Maxillofacial Surgery, University Hospital Ulm, Ulm, Germany
2. Department of Oral and Plastic Maxillofacial Surgery, Military Hospital Ulm, Ulm, Germany
3. Institute of Anatomy, Medical Faculty, University of Leipzig, Leipzig, Germany
4. Department of Cranio-Maxillofacial Surgery, University Medical Centre Mainz, Mainz, Germany