1. Department of Oral and Maxillofacial Surgery, College and Hospital of Stomatology, Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
2. Department of Pathology, College and Hospital of Stomatology, Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
3. Department of Disease Control and Prevention, College and Hospital of Stomatology, Guangxi Medical University, Nanning, Guangxi 530021, P.R. China