1. Department of Oral Histology and Pathology, School of Stomatology, The Fourth Military Medical University, Xi'an 710032, China
2. Xi'an Institute of Tissue Engineering & Regenerative Medicine, Xi'an 710032, China
3. Department of Periodontology & Oral Medicine, School of Stomatology, The Fourth Military Medical University, Xi'an 710032, China
4. Department of Anatomy, Osaka Dental University, 8-1 Kuzuhahanazono-cho, Hirakata-shi, Osaka 573-1121, Japan
5. Department of Dental Oriental Medicine, Osaka Dental University, 8-1 Kuzuhahanazono-cho, Hirakata-shi, Osaka 573-1121, Japan