1. Department of Conservative Dentistry, School of Dentistry, Pusan National University, Yangsan, Korea.
2. Department of Orthodontics, School of Dentistry, University of North Carolina, Chapel Hill, North Carolina.
3. Department of Prosthetic Dentistry, School of Dentistry, Pusan National University, Yangsan, Korea.
4. Department of Dental Materials, School of Dentistry and Biomedical Research Institute, Pusan National University, Yangsan, Korea.