**4. Supersonic and acid-etching method for Dentin geometry**

Compact structure inhibits the body fluid permeation and the cell invasion into the inside of the materials. Generally, this situation is called a material wall. Dentin and cortical bone have compact structure. We have been challenging to develop new dentin materials, using a supersonic and acid-etching technology (Akazawa et al., 2009; Akazawa et al., 2010; Akaza‐ wa et al., 2012). The surface structure design of dentin by the supersonic treatment might easily produce new functional scaffolds, which control the bio-absorption rate and the ad‐ sorption ability for protein and cells. Figure 9 shows the dissolution efficiencies of human dentin granules, which were demineralized for 5-45 min in 2.0%-HNO3 solutions by the su‐ personic treatment at 600W. A photograph inside Fig.9 is Digital microscopic view of DDM, dissolution for 30 min in 2.0%- HNO3 by the supersonic treatment at 600W and 28 kHz.

**Figure 9.** Dissolution efficiencies of human dentin granules, demineralized for 5-45 min in 2.0%-HNO3 by supersonic treatment at 600W. Inside photo: Digital microscopic DDM view, dissolution for 30 min in 2.0%- HNO3 by supersonic treatment at 600W and 28 kHz.

The innovative technology can create the adequate geometry and the surface structure of commercially available materials (Akazawa et al., 2012). Geometrical factors will improve the performance of biomaterials for bone regeneration (Reddi, 1974: Kuboki et al, 1995; Mur‐ ata et al, 1998). Biomaterials science should support and develop the advanced regenerative therapy using tooth-derived materials for patients in the near future.

## **Acknowledgment**

a: whole view, Note: the device developed for tooth transplantation and replantation b: fixed tooth, Note: corre‐ spondence to all teeth c: crown treatment, Note: periodontal ligament tissue protected from infected fine particles d:

a: initial X-ray photo: missing tooth (#46) and atrophied bone. Non-functional tooth (⇦) for DDM b: just after DDM graft. Non-functional tooth (⇨) for next tooth autograft c: tooth auto-transplantation at 4 months after DDM graft d: DDM autograft on perforated cortical bone before suture e: biopsy: mature bone connected with DDM residue (HE

root view, Note: keeping blood even after cutting and root canal filling

398 Advances in Biomaterials Science and Biomedical Applications

section)

**Figure 8.** Case 2: 24 year-old woman

**Figure 7.** New device for protecting periodontal ligament cells (Mr.FIX®, Tokyo Iken)

This project was greatly supported by the grant (consortium: 2004-5) of Japan Ministry of Economy, Trade and Industry, and Korea Tooth Bank Co. Ltd. The authors would like to thank WISM Mutoh Co. Ltd., and Tokyo Iken Co. Ltd., for developing the devices (Patents: 4866994, 4953276).
