1. Department of Periodontology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo 113-8549, Japan
2. Tsukuba Health-Care Dental Clinic, Tsukuba 305-0834, Japan
3. Clinical Dental Research Promotion Unit, Faculty of Dentistry, Tokyo Medical and Dental University (TMDU), Tokyo 113-8549, Japan
4. Department of Periodontology, Kanagawa Dental University, Yokosuka 238-8580, Japan
5. Department of Periodontology, Osaka Dental University, Osaka 540-0008, Japan
6. Oral Care Periodontics Center, Southern Tohoku General Hospital, Southern Tohoku Research Institute for Neuroscience, Koriyama 963-8052, Japan
7. Department of Lifetime Oral Health Care Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo 113-8510, Japan