1. Division of Gerodontology; School of Dental Medicine; University of Bern; Bern Switzerland
2. Division of Gerodontology and Removable Prosthodontics; University of Geneva; Geneva Switzerland
3. Division of Comprehensive Prosthodontics; Graduate School of Medical and Dental Sciences; Niigata University; Niigata Japan
4. Department of Oral Rehabilitation; Faculty of Dentistry; The University of Hong Kong; Hong Kong China