Hydroxyapatite (HA) porous materials for artifical human cancellous bone applications have been prepared via polymeric
sponge method. Suspensions of the nanostructured hydroxyapatite powders were prepared with a fixed amount of distilled
water and HA loading. After soaking cellulosic sponges into the suspension, the sponges were dried and then subjected to
heat-treatment at 600°C, followed by sintering at 1250°C for 1 h. No alteration in structure found after sintering. The effect
of sintering rate on the physical properties was also investigated in the study on two samples prepared based on a HA loading
of 44% in the starting slurry. The study found that the average apparent density of the porous bodies were 2.03 g/cm<sup>3</sup> and
1.69 g/cm<sup>3</sup> with porosites of 36 and 46 % for the faster and the slower sintering, respectively. Morphological evaluation of
the porous bodies shown that both the samples contained macropores of 200-500 μm diameter, which fulfill the minimum
pore size of 100 μm as medically required. Excellent pore interconnectivity was found in all the samples. The measurement
of compressive strength provided the values of 10.0 and 4.3 MPa for the faster and the slower sintering, respectively. It was
also shown that the difference in sintering rate influenced the crystallinity of porous HA obtained.
The paper reports on the effect of Ca/P ratio (1.57, 1.67 and 1.87) on the densification behaviour of nanocrystalline
hydroxyapatite (HA) prepared by a chemical precipitation method. Green compacts were prepared and sintered at
temperatures ranging from 1000°C to 1350°C. The sintered samples were characterized to determine the HA phase
stability, bulk density, hardness, fracture toughness and Young's modulus. XRD analysis revealed that the phase stability
was not disrupted throughout the sintering regime employed for HA having Ca/P ratio of 1.57 and 1.67. However,
secondary phases were observed for HA having a Ca/P ratio of 1.87 when sintered at high temperatures. In general,
regardless of Ca/P ratio, the HA bodies achieved > 95% relative density when sintered at 1100°C-1250°C. The results
indicated that the stoichiometric HA (Ca/P ratio = 1.67) exhibited the overall best properties, with the highest hardness
of 7.23 GPa and fracture toughness of 1.28 MPam1/2 being attained when sintered at 1000°C-1050°C.
Biomedical composites made of porous hydroxyapatite (HA) bonded with a biodegradable polymeric matrix gelatin have been prepared. This device is expected to be useful as an excellent bone graft with bioactive hydroxyapatite which will facilitate new bone formation and at the same time it could functions as drug delivery with a controlled release rate. In this preliminary report, we wish to present preparation and physical characterization of the biomedical composite and the non-biodegradable porous hydroxyapatite composing the matrix of the composite. Porous hydroxyapatite was prepared via polymeric sponge method using hydroxyapatite nanopowders which were prepared via sol-gel procedure. Suspensions of the sol-gel derived hydroxyapatite powder was prepared with an adjusted loading of hydroxyapatite, using a dispersant. After soaking cellulosic sponges into the suspension, the sponges were dried and then subjected to heat-treatment at 600°C, followed by sintering at 1250°C for 1h. Three types of porous hydroxyapatite samples have been prepared in various composition of hydroxyapatite suspension. Porous hydroxyapatite bodies produced from slurry with less hydroxyapatite powder content and more dispersant amount yielded higher porosity and thus causing weaker compressive strength. Compressive strengths varied between 0.67 and 1.94 MPa depending on the porosity of the sample. Porosity plays important role in gelatin loading; the amount of gelatin coated on the porous hydroxyapatite bodies depend on porosity and the gelatin concentration in water solution. The higher porosity the more gelatin can be absorbed by the porous body.