1. Department of Endodontics, Prosthodontics and Operative Dentistry, Biomaterials & Tissue Engineering Division, University of Maryland Dental School, Baltimore, MD 21201, USA
2. State Key Laboratory of Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu, China
3. Department of Orthodontics, School of Stomatology, Capital Medical University, Beijing, China
4. Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
5. Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
6. Department of Mechanical Engineering, University of Maryland, Baltimore County, MD 21250, USA