1. Division of Periodontology and Endodontology; Department of Oral Rehabilitation; School of Dentistry; Health Sciences University of Hokkaido; 1757 Kanazawa Ishikari-Tobetsu Hokkaido 061-0293 Japan
2. Division of Biomaterials and Bioengineering; Department of Oral Rehabilitation; School of Dentistry; Health Sciences University of Hokkaido; 1757 Kanazawa Ishikari-Tobetsu Hokkaido 061-0293 Japan