1. Department of Periodontology and Endodontology, Faculty of Dental Medicine, Hokkaido University, N13 W7, Kita-ku, Sapporo, Hokkaido 060-8586, Japan
2. Division of Periodontology and Endodontology, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Tobetsu-cho, Ishikari-gun, Hokkaido 061-0293, Japan
3. Support Section for Education and Research, Faculty of Dental Medicine, Hokkaido University,
N13 W7, Kita-ku, Sapporo, Hokkaido 060-8586, Japan
4. Department of Biomedical Materials and Engineering, Faculty of Dental Medicine, Hokkaido University, N13 W7, Kita-ku, Sapporo, Hokkaido 060-8586, Japan
5. Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Yamate-cho, Suita-shi, Osaka 564-8689, Japan