1. Department of Oral Biochemistry, Chonbuk National University, Jeonju, Korea;
2. Department of Dental Materials, Chonbuk National University, Jeonju, Korea;
3. Department of Preventive Dentistry, Institute of Oral Bioscience, School of Dentistry, Chonbuk National University, Jeonju, Korea;
4. Division of Advanced Materials Engineering, Chonbuk National University, Jeonju, Korea