1. Division of Cariology, Operative Dentistry and Endodontics, Department of Oral Health Science, Graduate School of Medical and Dental Sciences, Niigata University, Niigata 951-8514, Japan
2. Division of Oral Science for Health Promotion, Department of Oral Health and Welfare, Graduate School of Medical and Dental Sciences, Niigata University, Niigata 951-8514, Japan