1. Department of Oral Microbiology; Asahi University School of Dentistry, 1851-1 Hozumi; Mizuho Gifu 501-0296 Japan
2. Department of Microbiology; School of Dentistry; Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku; Nagoya 464-8650 Aichi Japan
3. Department of Community Oral Health; Asahi University School of Dentistry, 1851-1 Hozumi; Mizuho Gifu 501-0296 Japan
4. Department of Orthodontic; Asahi University School of Dentistry, 1851-1 Hozumi; Mizuho Gifu 501-0296 Japan