1. Department of Pathology Tokyo Dental College Tokyo Japan
2. Division of Oral Medicine and Pathology, Department of Human Biology and Pathophysiology, School of Dentistry Health Sciences University of Hokkaido Sapporo Japan
3. Advanced Research Promotion Center Health Sciences University of Hokkaido Sapporo Japan
4. Division of Disease Control and Molecular Epidemiology, Department of Oral Growth and Development, School of Dentistry Health Sciences University of Hokkaido Sapporo Japan