1. Department of Periodontology and Endodontology, Okayama University Dental School, 2-5-1 Shikata-cho, Okayama 700-8525, Japan
2. Department of Periodontology and Endodontology, Okayama University Dental School, 2-5-1 Shikata-cho, Okayama 700-8525, Japan, -u.ac.jp