1. Department of Fixed Prosthodontics, Osaka University Graduate School of Dentistry, Osaka, Japan
2. Department of Restorative Dentistry, Hokkaido Univer sity Graduate School of Dental Medicine, Hokkaido, Japan
3. Division for Interdisciplinary Dentistry, Osaka University Dental Hospital, Osaka, Japan
4. BIOMAT & University Hospitals Leuven, Department of Oral Health Sciences, KU Leuven (University of Leuven), Belgium