1. Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan
2. Department of Advanced Biomaterials, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan
3. Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
4. Kiyokawa Plating Industry Co., Ltd, Fukui-shi, Fukui, Japan
5. Shima Orthodontic Office, Fukui-Shi, Fukui, Japan