1. Nihon University Graduate School of Dentistry at Matsudo, Removable Prosthodontics and Geriatric Oral Health, Matsudo, Japan
2. Department of Gerodontology and Home Care Dentistry, School of Dentistry Aichi Gakuin University, Nagoya, Japan
3. Department of Removable Prosthodontics and Geriatric Oral Health, Nihon University School of Dentistry at Matsudo, Matsudo, Japan