1. Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
2. Department of Orthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, China.
3. Department of Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi'an, China.
4. Department of Oral Histology and Pathology, School of Stomatology, Fourth Military Medical University, Xi'an, China.