1. Department of Oral and Maxillofacial Surgery, Medical Faculty, Heinrich‑Heine‑University and University Hospital Düsseldorf, D-40225 Düsseldorf, Germany
2. Department of Pathology, Medical Faculty, University Hospital Cologne, D-50937 Cologne, Germany
3. Department of Pathology, Medical Faculty, Heinrich‑Heine‑University and University Hospital Düsseldorf, D-40225 Düsseldorf, Germany