1. Department of Oral Histology and Developmental Biology, School of Dentistry, Chosun University, Gwangju 61452
2. Department of Dental Hygiene, Graduate School of Public Health Science, Eulji University, Seongnam 13135
3. Department of Dental Hygiene, Hyejeon College, Hongseong 32244
4. Department of Dental Hygiene & Institute of Basic Science for Well-Aging, Youngsan University, Yangsan 50510, Korea