Takao Hanawa

Early bone formation around calcium‐ion‐implanted titanium inserted into rat tibia

Rat tibia tissue into which calcium ion (Ca2+)-implanted titanium was surgically placed was histologically analyzed to investigate the performance of the Ca(2+)-implanted titanium as a biomaterial. Calcium ions were implanted into only one side of titanium plates at 10(17) ions/cm2 and the Ca(2+)-treated titanium was surgically implanted into rat tibia for 2, 8, and 18 days. Tetracycline and calcein were used as hard-tissue labels. After excision of the tibia, the tissues were fixed, stained, embedded in polymethyl methacrylate, and sliced. The specimens were observed using a fluorescence microscope. A larger amount of new bone was formed on the Ca(2+)-treated side than on the untreated side, even at 2 days after surgery. In addition, part of the bone made contact with the Ca2(+)-treated surface. On the other hand, bone formation on the untreated side was delayed and the bone did not make contact with the surface. Mature bone with bone marrow formed in 8 days. Neither macrophage nor inflammatory cell infiltration was observed. The results indicated that Ca(2+)-implanted titanium is superior to titanium alone for bone conduction.

AMOUNT OF HYDROXYL RADICAL ON CALCIUM-ION-IMPLANTED TITANIUM AND POINT OF ZERO CHARGE OF CONSTITUENT OXIDE OF THE SURFACE-MODIFIED LAYER

To compare the surface properties of calcium-ion (Ca2+)-implanted titanium with those of titanium and to investigate the mechanism of bone conductivity of Ca2+-implanted titanium, amounts of hydroxyl radical of Ca2+-implanted titanium and titanium were estimated. Also, the point of zero charge (p.z.c.) of oxide constituting surface oxides of Ca2+-implanted titanium and titanium was determined. Results showed that the amount of active hydroxyl radical on Ca2+-implanted titanium was found to be significantly larger than that on titanium, indicating that the number of electric-charging sites of Ca2+-implanted titanium in electrolyte is more than that of titanium. The p.z.c. values of rutile (TiO2), anatase (TiO2), and perovskite (CaTiO3), were estimated to be 4.6, 5.9, and 8.1, respectively. Thus, Ca2+-implanted titanium surface is charged more positively in bioliquid than titanium, accelerating the adsorption of phosphate ions.