1. Department of Oral Disease Research, National Institute for Longevity Sciences, National Center for Geriatrics & Gerontology, Obu, Aichi.
2. Department of Developmental Anatomy & Regenerative Medicine, National Defense Medical College, Tokorozawa, Saitama 359-8513, Japan
3. Department of Pediatric Dentistry, School of Dentistry, Aichigakuin University, Nagoya, Aichi 464-8651, Japan
4. Department of Endodontology, School of Dentistry, Aichigakuin University, Nagoya, Aichi 464-8651, Japan