1. Section of Biomaterials, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, 3‐1‐1 Maidashi, Higashi‐ku, 812‐8582 Fukuoka, Japan
2. Section of Removable Prosthodontics, Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University,3‐1‐1 Maidashi, Higashi‐ku, 812‐8582 Fukuoka, Japan
3. Section of Bioengineering, Department of Dental Engineering, Division of Biomedical Science, Fukuoka Dental College, 2‐15‐1 Tamura, Sawara‐ku, 814‐0193 Fukuoka, Japan
4. Institute for Biomedical Research and Education, Yamaguchi University Science Research Center,1‐1‐1 Minamiogushi, Ube City, 755‐8505 Yamaguchi, Japan