1. School and Hospital of Stomatology, Peking University, Beijing, China
2. School of Stomatology, Dalian Medical University, Dalian, Liaoning, China
3. Department of Engineering Physics, Tsinghua University, Beijing, China
4. Oral Imaging Center, Department of Oral Health Sciences, KU Leuven, Leuven, Belgium
5. Oral and Maxillofacial Radiology, School of Dentistry, Temple University, Philadelphia, PA, USA
6. Department of Computer and Information Sciences, Temple University, Philadelphia, PA, USA