HANAICHI Takamasa N.I.T., Dept.Electri.and Comput.Eng., Assistant, 工学部, 助手 (90252311)
BAN Seiji School of Dentistry, Aichi-Gakuin Univ., Lecturer, 歯学部, 講師 (10159105)
NOWAK Roman N.I.T., Dept.Electri.and Comput.Eng., Associate Prof., 工学部, 助教授 (90242916)
|Budget Amount *help
¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 1996: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1995: ¥5,500,000 (Direct Cost: ¥5,500,000)
The present research deals with the surface modification of the hydroxyapatite (HA) containing glass (G) coated titanium (or titanium alloy) composite, so called HA-G-Ti functionally gradient materials providing both the bioactivity due to HA and the mechanical strength of Ti, and the bonding of bone to the modified composites during an early stage in the implantation into femora of rabbit and dog. The results obtained in in vitro and in vivo experiments are summarized as follows.
(1) The reaction of glass, alumino-borosilicate glass used for the preparation of the HA-G-Ti composite, with HA with different degrees of crystallinitiy and properties during the firing process was examined by thermal analyzes and X-ray diffraction, as well as the morphological aspect by SEM observation. The formation of boron containing apatite phase was confirmed, especially remarkable for the case of low crystallinity HA.
(2) Biological apatite, in which the main component is carbonate apatite, was deposite
d electrochmically (electrolyte temp.4-92ﾟC,current density 1.3 and 13 mA/cm^2) and hydrothermal-electrochemically (electrolyte temp.100-200ﾟC,current density 12.5 mA/cm^2) in modified simulated body fluid (SBF), and then these apatite with different shapes such as granular, flaky or plate-like, needle-like ones were characterized by FT-IR,FE-SEM and TEM.the grown crystal rods like a single crystal, formed under the hydrothermal electrochemical condition, have a definite hexagonal crystal habit.
(3) Octa-, tetra- and tri- calcium phosphates (OCP,TTCP and TCP) were synthesized and their phase transformation to hydroxyapatite studied. Three kinds of CP [HA (1), TTCP (2) and alpha-TCP/TTCP (3)]-glass-Ti composite implants were submitted to animal test (in dog femur). It has been found that the hydrolysis reaction for TTCP prevents the apposition of bone to the implant.
(4) The modified HA-G-Ti composites covered with needle-like biological apatite were implanted in femur of Japanese white rabbit (and also dog femur) for a short period of time (3,6 and 9 weeks). It has been found through the experiments of the bonding strength (BS) between bone and the implants (by pullout test) that the electrochemical surface treatment on the HA-G-Ti composite enhances markedly the bone bonding effect at an early stage of 3 and 6 week implantation, i.e., the value of BS is 1.5 and 1.3 times large as compared with the conventional implant. The microstractural analysis of the interface between bone and implants were also performed. Less