1. Division of Removable Prosthodontics, Department of Oral Rehabilitation, Fukuoka Dental College, Fukuoka, Japan
2. Department of Biomaterials Science and Turku Clinical Biomaterials Centre - TCBC, Institute of Dentistry, University of Turku, Turku, Finland
3. Central Dental Laboratory, Fukuoka Dental College Medical & Dental Hospital, Fukuoka, Japan