1 The First Department of Oral and Maxillofacial Surgery & Oral Plastic and Aesthetic Surgery, Hospital of Stomatology, Jilin University, Changchun, China.
2 Histology and Embryology, College of Basic Medical Sciences, Jilin University, Changchun, China.
3 The First Department of Oral and Maxillofacial Surgery & Oral Plastic and Aesthetic Surgery, Hospital of Stomatology, Jilin University, Changchun, China. Electronic address: linn@jlu.edu.cn.