1 Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Japan.
2 Department of Oral and Maxillofacial Prosthodontics, Graduate School of Medical and Dental Sciences, Kagoshima University, Japan.
3 Department of Oral Rehabilitation and Regenerative Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Japan.
4 Division of Molecular and Regenerative Prosthodontics, Tohoku University Graduate School of Dentistry, Japan. Electronic address: egu@dent.tohoku.ac.jp.