1. Department of Special Care Dentistry, Nagasaki University Hospital, Nagasaki, Japan
2. Department of Fixed Prosthodontics, Nihon University School of Dentistry, Tokyo, Japan
3. Department of Prosthetic Dentistry, School of Dentistry, Ohu University, Koriyama, Japan
4. President of Japan Prosthodontic Society, Division of Removable Prosthodontics, Department of Restorative and Biomaterials Sciences, Meikai University School of Dentistry, Sakado, Japan