1. Assistant professor, Department of Prosthodontics, School of Dental Medicine, University of Bern, Bern, Switzerland;
2. postgraduate student, Department of Prosthodontics, School of Dental Medicine, University of Bern, Bern, Switzerland;
3. chair, Department of Maxillofacial Surgery, University of Bern, Bern, Switzerland;
4. chair, Department of Prosthodontics, School of Dental Medicine, University of Bern, Bern, Switzerland