1. Division of Applied Oral Sciences, Nihon University Graduate School of Dentistry, Chiyoda-ku, Tokyo, Japan
2. Department of Physiology, Nihon University School of Dentistry, Chiyoda-ku, Tokyo, Japan
3. Department of Microbiology, Nihon University School of Dentistry, Chiyoda-ku Tokyo, Japan
4. Department of Periodontology, Nihon University School of Dentistry, Chiyoda-ku, Tokyo, Japan