1Department of Periodontology School of Dentistry, Chonnam National University, Korea.
2Dental Science Research Institute, 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@chonnam.ac.kr