1. Department of Complete Denture Prosthodontics, Nihon University School of Dentistry, Tokyo, Japan;
2. Division of Advanced Dental Treatment, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan;
3. Division of Applied Oral Sciences, Nihon University Graduate School of Dentistry, Tokyo, Japan;
4. Department of Pathology, Nihon University School of Dentistry, Tokyo, Japan;
5. Division of Immunology and Pathobiology, Nihon University School of Dentistry, Tokyo, Japan