1. Department of Restorative, Preventive and Pediatric Dentistry, School of Dental Medicine, University of Bern, 3012 Bern, Switzerland
2. Department of Reconstructive Dentistry and Geriodontology, School of Dental Medicine, University of Bern, 3012 Bern, Switzerland
3. Division of Gerodontology and Removable Prosthodontics, University Clinics of Dental Medicine, University of Geneva, 1205 Geneva, Switzerland
4. Department of Periodontology, School of Dental Medicine, University of Bern, 3012 Bern, Switzerland