1. Department of Stomatology, Zhongshan Hospital, Fudan University, Shanghai 200031, P.R. China
2. Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P.R. China
3. Department of Hard Tissue Research, Graduate School of Oral Medicine, Matsumoto Dental University, Shiojiri, Nagano 399‑0781, Japan
4. Department of Hard Tissue Research, Institute for Oral Science, Matsumoto Dental University, Shiojiri, Nagano 399‑0781, Japan