1. Department of Special Needs Dentistry, Division of Dental Education, School of Dentistry; Showa University; Tokyo Japan
2. Department of Oral Microbiology, School of Dentistry; Showa University; Tokyo Japan
3. Department of Oral Biomaterials and Technology, School of Dentistry; Showa University; Tokyo Japan
4. Department of Dentistry and Oral Surgery; Ushiku Aiwa General Hospital; Ibaraki Japan