1. Department of Stomatology, The First Affiliated Hospital of Jinzhou Medical University, Jinzhou, China;
2. Department of Prosthodontics, Tianjin Stomatological Hospital, Tianjin, China;
3. Department of Stomatology, Beijing DCN Orthopaedic Hospital, Beijing, China;
4. Department of Ultrasonography, The First Affiliated Hospital of Jinzhou Medical University, Jinzhou, China