1Department of Periodontology, School of Dentistry, Chonnam National University, Korea.
2Dental Science Research Institute, School of Dentistry, Chonnam National University, Korea.
3Department Metallurgical Engineering, College of Engineering, Chonnam National University, Korea.
Corresponding author: Young-Joon Kim, Department of Periodontology, School of Dentistry, Chonnam National University, 5, Hak 1 Dong, Dong-gu, Gwangju, 501-746, Korea. youngjun@chonam.ac.kr