1. Department of Oral Histology and Developmental Biology, School of Dentistry, Chosun University, Gwangju 61452, Korea
2. Department of Dental Hygiene, Dong-Pusan College, Busan 48000, Korea
3. Department of Dental Hygiene, Graduate School of Public Health Science, Eulji University, Seongnam 13135, Korea
4. Department of Dental Hygiene, College of Health Science, Youngsan University, Yangsan 50510, Korea