1. Department of Oral Microbiology, College of Dentistry, Gangneung-Wonju National University, Gangneung, Korea.
2. Research Institute of Oral Science, Gangneung-Wonju National University, Gangneung, Korea.
3. Department of Preventive and Public Health Dentistry, College of Dentistry, Gangneung-Wonju National University, Gangneung, Korea.