The development of taylor-made materials with biomedical function.

• Project/Area Number: 17390521
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 補綴理工系歯学
• Research Institution: The University of Tokushima
• Principal Investigator: ICHIKAWA Tetsuo The University of Tokushima, Institute of Health Bio-Sciences, Graduate School, Professor (90193432)
• Co-Investigator(Kenkyū-buntansha): OKA Kenji The University of Tokushima, Institute of Health Bio-Sciences, Graduate School, Research Assistant Professor (40253215) ; TOMOTAKE Yoritoki The University of Tokushima, Institute of Health Bio-Sciences, Graduate School, Research Lecturer (70263853) ; NAGAO Kan The University of Tokushima, Institute of Health Bio-Sciences, Graduate School, Associate Professor (30227988) ; ASAOKA Kenzo The University of Tokushima, Institute of Health Bio-Sciences, Graduate School, Professor (50014189) ; ISHIDA Yuuichi The University of Tokushima, Medical & Dental Hospital, Administrative Staff (90403708)
• Project Period (FY): 2005 – 2007
• Project Status: Completed (Fiscal Year 2007)
• Budget Amount: ¥11,520,000 (Direct Cost: ¥11,100,000、Indirect Cost: ¥420,000); Fiscal Year 2007: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000); Fiscal Year 2006: ¥2,600,000 (Direct Cost: ¥2,600,000); Fiscal Year 2005: ¥7,100,000 (Direct Cost: ¥7,100,000)
• Keywords: Dentistry / Biomaterial / Titanium / Porous Material / 複合材料・物性

Research Abstract

Porous titanium has been developing recently for biomedical application. It is difficult, however, to make a various shape, since they are formed and sintered in a mold. In this study, a mixture of titanium powder and an inlay wax binder was developed for moldless forming and sintering without any mold. The formability of the mixture, the dimensional change after sintering, and the physical, mechanical and biological properties of the sintered porous titanium produced were evaluated.
Mixture of Ti powder and wax binder (mixing ratio of wax was 10 mass%) was formed manually at 70℃. After debindering, the specimen was sintered in Ar at 1100℃ without any mold. The sintering times were 1, 5, and 10 hours. The shrinkage, porosity, absorption rate and mechanical property were measured. To examine the bioactivity of the specimen, osteoblast-like cells were cultured. Implantation tests of three types of titanium specimen were performed ; commercial porous titanium as a control, porous titanium produced by our process, and the porous titanium by our process saturated by a drug enhancing bone formation. Histological observations of osteogenesis and bone contact ratio measurement were performed.
The bending strength, compression strength and elastic modulus were increased with increasing sintering time. The strengths were higher than that of cortical bone and the modulus was similar to that of cortical bone. The shrinkage was increased with it, while the porosity and absorption rate were decreased with it. These effects of sintering time on mechanical properties and absorption rate were mainly due to the reduction of porosity with progress of sintering. The osteoblast-like cells grew well and evenly adhered on the surface of all specimens. The bone contact ratios of porous titanium by our process were significantly higher than that of control. However, the effect of the drug was not significant. On the contrary, the thickness of new bone around the specimen with the drug was significantly larger than that without drug.
The high formability of the process in this research showed a clear advantage for forming and processing of bone substitution units. The porous titanium showed no inferiority in strength compared with the cortical bone and similar elastic modulus with it. The porous titanium demonstrated sufficient bioactivity and bone conductivity for biomedical applications, and good functionality for DDS.