Y Hu1, L F Zhu2, C S Xu3. 1. Department of Stomatology, Suzhou Kowloon Hospital, Shanghai Jiao Tong University, School of Medicine, Suzhou 215028, China (is now working on the Department of Stomatology, The Affiliated Suzhou Science & Technology Town Hospital of Nanjing Medical University, Suzhou 215153, China). 2. Department of Stomatology, The First Affiliated Hospital of Soochow University, Suzhou 215006, China. 3. Department of Radiation Oncology, Suzhou Kowloon Hospital, Shanghai Jiao Tong University, School of Medicine, Suzhou 215028, China.