1. Department of Dental Materials, School of Dentistry and Medical Research Institute, Pusan National University, Yangsan, Korea.
2. Department of Conservative Dentistry, School of Dentistry, Pusan National University, Yangsan, Korea.
3. Department of Biomedical Engineering, School of Medicine, Pusan National University, Yangsan, Korea.
4. College of Dentistry, University of Tennessee Health Science Center, Memphis, Tennessee.