1. School of Dentistry, Hainan Medical University, Haikou, P.R. China
2. Department of Dentistry, The First Affiliated Hospital of Hainan Medical University, Haikou, P.R. China
3. The 928th Hospital of People’s Liberation Army Joint Logistic Support Force, Haikou, P.R. China
4. Department of Dentistry, The Second Affiliated Hospital of Hainan Medical University, Haikou, P.R. China
5. School of International Education, Hainan Medical University, Haikou, P.R. China
6. Department of Health Management Center, The First Affiliated Hospital of Hainan Medical University, Haikou, P.R. China.