1. Department of Dental Science, Graduate School, Kyungpook National University, Daegu, Korea.
2. Department of Conservative Dentistry, Kyungpook National University, Daegu, Korea.
3. Department of Dental Biomaterials, School of Dentistry, Kyungpook National University, Daegu, Korea.
4. Institute for Biomaterials Research and Development, Kyungpook National University, Daegu, Korea.