1. Joint Research Laboratory of Advanced Functional Materials Science, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan
2. Department of Dental Biomaterials, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka 565-0871, Japan
3. Department of Cariology, Restorative Sciences and Endodontics, University of Michigan School of Dentistry, 1011 N University Ave, Ann Arbor, MI 48109, USA