1. Department of Periodontology, State Key Laboratory of Military Stomatology and National Clinical Research Center for Oral Diseases, School of Stomatology Fourth Military Medical University Xi'an People's Republic of China
2. Department of Pediatric Dentistry, College of Stomatology Xi'an Jiaotong University Xi'an People's Republic of China
3. Department of General Dentistry and Emergency, State Key Laboratory of Military Stomatology and National Clinical Research Center for Oral Diseases, School of Stomatology Fourth Military Medical University Xi'an People's Republic of China