1. Department of Biomaterials, Faculty of Dental Science, Kyushu University 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
2. Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan