1. Department of Periodontology, School of Dentistry, Aichi Gakuin University, Chikusa-ku, Nagoya, Aichi, Japan.
2. School of Dentistry, Kaohsiung Medical University, Sanmin District, Kaohsiung City, Taiwan (R.O.C.).
3. Department of Preventive Dentistry and Dental Public Health, Aichi Gakuin University, Chikusa-ku, Nagoya, Aichi, Japan.