1. Department of Oral Physiology, Meikai University, School of Dentistry, Sakado, Saitama 350-0283, Japan.
2. Department of Technical Section, Meikai University, School of Dentistry, Sakado, Saitama 350-0283, Japan.
3. Department of Oral Diagnosis, Meikai University, School of Dentistry, Sakado, Saitama 350-0283, Japan.