1. Department of Reconstructive Dentistry Faculty of Odontology University of Iceland Reykjavik Iceland
2. Division of Fixed Prosthodontics and Biomaterials University Clinics for Dental Medicine University of Geneva Geneva Switzerland
3. Department of Maxillofacial, Oral and Plastic Surgery Faculty of Dentistry Moscow State University of Medicine and Dentistry Moscow Russia
4. Department of Prosthetic Dentistry Faculty of Medicine Center for Dental Medicine, Medical Center – University of Freiburg Freiburg Germany