• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1177-1182
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• 2002

Highly surfaced and porous hydroxyapatite body was artificially formed on the surface of a shell through a reaction with phosphatic solutions. As a result of qualitative observation, hydroxyapatite seemed to be crystallized by solution-precipitation process accelerated by the nucleation surface of a shell. The process of formation of hydroxyapatite layer was as follows. 1. Dense nucleation and growth on the surface of solid phase 2. Formation of microporous layer by contact and entanglement between crystallines 3. diffusion of solution through the porous layer and thickness growth of layer towards inside

• Journal of the Korean Ceramic Society
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• v.26 no.2
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• pp.171-178
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• 1989

In order to develope hydroxyapatite ceramics which has mechanical strength as bio-implant materials and get the basic data for the study and application of biocompatibility, hydroxyapatite was synthesized at Ca/P=1.67~1.75, pH 7~11 by precipitation method. Using prepared powders, the sintered body, fluorine substituted body and the porous body was formed and their properties were investigated. The sample obtained in condition of Ca/P=1.67, pH 7 and sintering at 1,15$0^{\circ}C$ was decomposed to $\beta$-tricalcium phosphate, and co-existed with hydroxyapatite. Hydroxyapatite synthesized at pH 11 was not easily decomposed to $\beta$-tricalcium phosphate at sintering process. The substitution of a small amount of fluorine for hydroxyapatite prevented hydroxyapatite from being decompsed to $\beta$-tricalcium phosphate. Hydroxyapatite ceramics which substited of 10% fluorine was prepared at 1,15$0^{\circ}C$, and the valueof bending strength for this body were found to be 112MPa.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.3
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• pp.284-293
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• 1994

The various methods of preparation for the porous hydroxyapatite ceramics using naphthalene, $H_20_2$ and chlorinated paraffine with $H_20_2$ were investigated. And then the prepared orous hydroxyapatite ceramics were characterized by XRD, SEM, FT-IR and the apparent porosity. The pore size of porous hydroxyapatite ceramics was controlled by the content and size of naphthalene granular. It was found that the porosity of it was increased with the amount of naphthalene, but the bending strength was decreased. The application of hydrogen peroxide produced porous materials like a sponge tissue, but the porosity and the shape of sintered body were hardly controlled. In the case of using chlorinated paraffine with the simultaneous addition of hydrogen peroxide, the sponge tissue was obtained and also could be controlled from 50 up to about 65% porosity of it.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.3950-3956
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• 2012

In order to improve the bioactivity and mechanical properties of hydroxyapatite (HAp), chitosan (Chi) was in situ combined into HAp to fabricate a composite scaffold by a sublimation-assisted compression method. A highly porous film with sufficient mechanical strength was prepared and the bioactivity was investigated by examining the apatite formed on the scaffolds incubated in simulated body fluid. In addition, the cytotoxicity of the HAp/Chi composite was studied by evaluating the viability of murine fibroblasts (L-929 cells) exposed to diluted extracts of the composite films. The apatite layer was assessed using scanning electronic microscopy, inductively coupled plasma-optical emission spectrometry and weight measurement. Composite analysis showed that a layer of micro-sized, needle-like crystals was formed on the surface of the composite film. Additionally, the WST-8 assay after L-929 cells were exposed to diluted extracts of the composite indicated that the HAp/Chi scaffold has good in vitro cytocompatibility. The results indicated that HAp/Chi composites with porous structure are promising scaffolding materials for bone-patch engineering because their porous morphology can provide an environment conductive to attachment and growth of osteoblasts and osteogenic cells.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.390-395
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• 2011

The objective of our study was to produce an imitation bone material consisting of hydroxyapatite with a compact and spongy structure. This study shows the ideal content of $SiO_2$ and the sintering temperature to produce imitation bone that has the mechanical properties of natural bone. On the basis of our determination of the ideal conditions, a compact part was produced and its mechanical properties were tested. A compact part made of 0.5 wt% $SiO_2$ and sintered at $1350^{\circ}C$ showed excellent mechanical properties. The bioactivity of the compact part under this condition was tested, and it was found to be bioactive. The porous part was produced by controlling the powder size, and the dual structure was manufactured by combining the compact and porous parts. A water permeability test confirmed that the dual structure had an interconnected pore structure. Therefore, this dual-body structure is feasible for use in the creation of implants.

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.1-26
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• 1996

This study was performed to estimate the effects of cultured bone cell inoculated on porous type hydroxyaptite for the regeneration of the artificial alveolar bone defect. In this experiment 3 beagle dogs were used, and each of them were divided into right and left mandible. Every surgical intervention were performed under the general anesthesia by using with intravenous injection of Pentobarbital sodium(30mg/Kg). To reduce the gingival bleeding during surgery, operative site was injected with Lidocaine hydrochloride(l:80,000 Epinephrine) as local anesthesia. After surgery experimental animal were feeded with soft dietl Mighty dog, Frisies Co., U.S.A.) for 1 weeks to avoid irritaion to soft tissue by food. 2 months before surgery both side of mandibular 1st premolar were extracted and bone chips from mandibular body were obtained from all animals. Bone cells were cultured from bone chips obtained from mandible with Dulbecco's Modified Essential Medium contained with 10% Fetal Bovine Serum under the conventional conditions. Porous type hydroxyapatite were immerse into the high concentrated cell suspension solution, and put 4 hours for attachin the cells on the surface of hydroxyapatite. Graft material were inserted on the artificial bone defect after 3 days of culture. Before insertion of cellinoculated graft material, scanning electronic microscopic observation were performed to confirm the attachment and spreading of cell on the hydroxyapatite surface. 3 artificial bone defects were made with bone trephine drill on the both side of mandible of the experimental animal. First defect was designed without insertion of graft material as negative control, second was filled with porous replamineform hydroxyapatite inoculated with cultured bone marrow cells as expermiental site, and third was filled with graft materials only as positive control. The size of every artificial bone defect was 3mm in diameter and 3mm in depth. After the every surgical intervention of animals, oral hygiene program were performed with 1.0% chlorhexidine digluconate. All of the animals were sacrificed at 2, 4, 6 weeks after surgery. For obtaining histological section, tissus were fixed in 10% Buffered formalin and decalcified with Planko - Rycho Solution for 72hr. Tissue embeding was performed in paraffin and cut parallel to the surface of mandibular body. Section in 8um thickness of tissue was done and stained with Hematoxylin - Eosin. All the specimens were observed under the light microscopy. The following results were obtained : 1. In the case of control site which has no graft material, less inflammatory cell infiltration and rapid new bone forming tendency were revealed compared with experimental groups. But bone surface were observed depression pattern on defect area because of soft tissue invasion into the artificial bone defect during the experimental period. 2. In the porous hydroxyapatite only group, inflammatory cell infiltration was prominet and dense connective tissue were encapsulated around grafted materials. osteoblastic activity in the early stage after surgery was low to compared with grafted with bone cells. 3. In the case of porous hydroxyapatite inoculated with bone cell, less inflammatory cell infiltration and rapid new bone formation activity was revealed than hydroxyapatite only group. Active new bone formation were observed in the early stage of control group. 4. The origin of new bone forming was revealed not from the center of defected area but from the surface of preexisting bony wall on every specimen. 5. In this experiment, osteoclastic cell was not found around grafted materials, and fibrovascular invasion into regions with no noticeable foreign body reaction. Conclusively, the cultured bone cell inoculated onto the porous hydroxyapatite may have an important role of regeneration of artificial bone defects of alveolar bone.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.155.2-155
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• 2003

• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.214-218
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• 2000

Hydroxyapatite (HA) and $\beta$-tricalcium phosphate ($\beta$-TCP) are bio-compatible materials with bones and teeth. HA has been widely applied as bone substitutes because of chemical stability in vivo, while $\beta$-TCP has higher resorbability than HA when the material is implanted in a bone defect. In the present study, both HA and $\beta$-TCP porous ceramics were soaked in the simulated body fluid in order to investigate the reaction between the materials and the fluid. After the soaking test, carbonate hydroxyapatite was formed on HA surface at 1 week, and then the amount of precipitates increased with increasing period of the soaking test. While $\beta$-TCP was not dissolved in the fluid, carbonate hydroxyaopatite was also formed on $\beta$-TCP surface after 12 weeks, and the amount of precipitates was less than that on HA. In vitro behavior of HA was similar to that in vivo, but in vitro behavior of $\beta$-TCP was not similar to that in vivo.