1. Department of Oral Frontier Biology; Center for Frontier Oral Science; Osaka University Graduate School of Dentistry; Suita Osaka 565-0871 Japan
2. Division of Special Care Dentistry; Osaka University Dental Hospital; Suita Osaka 565-0871 Japan
3. Department of Preventive Dentistry; Osaka University Graduate School of Dentistry; Suita Osaka 565-0871 Japan
4. Department of Oral and Maxillofacial Surgery; Osaka University Graduate School of Dentistry; Suita Osaka 565-0871 Japan
5. Center for Oral Health and Systemic Disease; School of Dentistry; University of Louisville; Louisville KY 40202 USA