1. Oral and Maxillofacial Surgery Department of Oral Patho‐biological Science Graduate School of Dental Medicine Hokkaido University Sapporo Japan
2. Department of Oral and Maxillofacial Surgery Kanazawa University Graduate School of Medical ScienceKanazawa University Kanazawa Japan
3. Gerodontology, Department of Oral Health Science Graduate School of Dental Medicine Hokkaido University Sapporo Japan