1. Department of Pharmacology; Nihon University School of Dentistry; Tokyo 101-8310 Japan
2. Department of Pediatric Dentistry; Nihon University School of Dentistry; Tokyo 101-8310 Japan
3. Division of Oral and Craniomaxillofacial Research; Dental Research Center, Nihon University School of Dentistry; Tokyo 101-8310 Japan
4. Molecular Imaging Research Center; RIKEN Kobe 650-0047 Japan