1. Department of Pediatric Internal Medicine, Qilu Hospital of Shandong University (Qingdao), Qingdao, Shandong 266000, P.R. China
2. Department of Pediatrics, People's Hospital of Chiping, Liaocheng, Shandong 252000, P.R. China
3. PIVAS, The People's Hospital of Zhangqiu Area, Jinan, Shandong 250200, P.R. China
4. Department of Stomatology, The People's Hospital of Zhangqiu Area, Jinan, Shandong 250200, P.R. China