1. South China Center of Craniofacial Stem Cell Research Hospital of Stomatology Guangdong Provincial Key Laboratory of Stomatology Sun Yat‐Sen University Guangzhou 510080 P. R. China
2. Department of Pediatric Dentistry School and Hospital of Stomatology China Medical University Shenyang 110122 P. R. China
3. Key Laboratory of Stem Cells and Tissue Engineering, Ministry of Education Sun Yat‐Sen University Guangzhou 510080 P. R. China