1. Department of Conservative Dentistry, Gangnam Severance Dental Hospital, College of Dentistry, Yonsei University, Seoul 06273, Republic of Korea
2. Department of Conservative Dentistry, Hallym Hospital, Hallym University, Anyang 14068, Republic of Korea
3. Microscope Center, Department of Conservative Dentistry and Oral Science Research Center, College of Dentistry, Yonsei University, Seoul 03722, Republic of Korea