1. Department of Reconstructive Dentistry and Gerodontology School of Dental Medicine University of Bern Bern Switzerland
2. Division of Gerodontology and Removable Prosthodontics University Clinics of Dental Medicine University of Geneva Geneva Switzerland
3. Comprehensive Dental Care Unit The Nippon Dental University Niigata Hospital Niigata Japan
4. Division of Phoniatrics Department of Otorhinolaryngology Head Neck Surgery, Inselspital University of Bern Bern Switzerland