1. Robert K. Schenk Laboratory of Oral Histology; University of Bern; Bern Switzerland
2. Department of Periodontology; University of Bern; Bern Switzerland
3. Department of Oral Surgery and Stomatology; University of Bern; Bern Switzerland
4. Clinic of Cranio-Maxillofacial and Oral Surgery; University of Zürich; Zürich Switzerland
5. Department of Oral & Maxillofacial Surgery; Red Cross Hospital; Kassel Germany