• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.652-656
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• 2007

Hydroxyapatite [Ca10(PO4)6(OH)2, HAp] and titanium(Ti) metal are known to be excellent materials with high affinities for natural bone through the apatite. Tricalcium phosphate [Ca3(PO4)2, TCP] is a promising alternative material because it is similar to HAp in its physical properties and biocompatibility. To examine the influence of hydroxyapatite, tricalcium phosphate, pure titanium and pre-treated titanium on osteopontin expression in osteoblasts, RNA was extracted from proliferated and cultured osteoblast cells and OPN mRNA expression was observed by RT-PCR.

• Journal of the Korean Vacuum Society
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• v.6 no.S1
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• pp.27-33
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• 1997

Recently ion beam assistant deposition (IBAD) was successfully used to produce a dense ultra-adherent and pinhole-free hydroxyapatite (HAp) layer on alumina substrate. After that the HAp-coated alumina was immersed in 20ppm and 100ppm $AgNO_3$ solution at room temperature for 48 hours to carry out the ions exchange between $Ag^+\;and\;Ca^+$ in HAp. The obvious antimicrobial effect against E.Coli, P. Aeruginosa and S. Epidermidis was observed in the samples treated with 20ppm $AgNO_3$ Solution, In contrast to this the untreated samples did not show any bactericidal effect. Scanning electron microscope(SEM) study showed that Ag homogeneously distributed on the surface. X-ray diffraction (XRD) demonstrated that the surface structure in the samples without Ag was HAp whereas with Ag is HAp and AgCaP. It appears that silver ions exchange with calcium ions in HAp does not cause significant changes in the structure of HAp coatings.

• Journal of the Korean Ceramic Society
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• v.42 no.10 s.281
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• pp.660-664
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• 2005

Hydroxyapatite powder was injected into the tooth after decayed tooth clinic. The microstructure of tooth was observed after a tooth extraction in the body. The hydroxyapatite powder was stiffened and the junction of hydroxyapatite powder and tooth was observed. The Ca/P atomic ratio of hydroxyapatite-tooth boundary was higher than hydroxyapatite matrix. And microhardness of hydroxyapatite matrix was 92.4 Hv. The junction of hydroxyapatite powder and tooth was due to the $Ca^{2+}$ ion shift of hydroxyapatite or the firm waxy body was due to setting of hydroxyapatite powder.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.975-982
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• 2008

We investigated whether transplantation of osteogenically differentiated bone marrow-derived mesenchymal stem cells (BMMSCs) and the use of an hydroxyapatite (HAp) scaffold can enhance the in vivo bone formation efficacy of human BMMSCs. Three months after implantation to the subcutaneous dorsum of athymic mice, transplantation of osteogenically differentiated human BMMSCs increased the bone formation area and calcium deposition to 7.1- and 6.2-folds, respectively, of those of transplantation of undifferentiated BMMSCs. The use of the HAp scaffold increased the bone formation area and calcium deposition to 3.7- and 3.5-folds, respectively, of those of a polymer scaffold. Moreover, a combination of transplantation of osteogenically differentiated BMMSCs and HAp scaffold further increased the bone formation area and calcium deposition to 10.6- and 9.3-folds, respectively, of those of transplantation of undifferentiated BMMSCs seeded onto polymer scaffolds. The factorial experimental analysis showed that osteogenic differentiation of BMMSCs prior to transplantation has a stronger positive effect than the HAp scaffold on in vivo bone formation.

• Korean Journal of Materials Research
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• v.16 no.11
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• pp.715-718
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• 2006

Porous hydroxyapatite (HAp) scaffolds have been prepared by using the slurry including HAp and magnesia based on the replication of polymer sponge substrate. The influence of MgO content in slurry on the pore morphology and size, density, porosity, and mechanical strength of porous HAp scaffolds was investigated. The obtained scaffolds with average pore sizes ranging 150 to 300 mm had open, relatively uniform, and interconnected porous structure regardless of MgO content. As the MgO content increased, the pore network frame of scaffolds became to be relatively stronger, even though the pore size was not much changed. The compressive strength of the scaffolds increased rapidly with the increase of MgO content because of increasing the pore wall thickness and density of the scaffolds. As a result, the porosity, density, and compressive strength of the porous HAp scaffolds prepared by the sponge method were significantly affected by the addition of MgO.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.152.1-152.1
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• 2007

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.5
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• pp.203-207
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• 2019

Calcium phosphates such as hydroxyapatite (HAp), tricalcium phosphate (${\beta}$-TCP), and biphasic calcium phosphate (BCP, HAp/${\beta}$-TCP) have been prepared via hydrothermal treatment. The synthesis was conducted by reacting ($Ca(OH)_2$) aqueous solution with phosphoric acid ($H_3PO_4$) under different hydrothermal synthesis conditions (temperatures up to $150^{\circ}C$ and pH lower than 12). The effects of initial precursor Ca/P ratio (1.30, 1.50 and 1.67) and post heat treatment on the phase evolution behavior of the powders and sintered ceramics were investigated. The phases of resulting powders and sintered ceramics were controllable by adjusting the initial Ca/P ratio. A single HAp phase without any noticeable second phase was obtained for the initial Ca/P ratio of 1.67 in the overall heat treatment range. Pure ${\beta}$-TCP and biphasic calcium phosphate (HAp/${\beta}$-TCP) were synthesized from precursor solutions having Ca/P molar ratios of 1.30 and 1.50, respectively, after having been heat treated at $900^{\circ}C$ or higher. Dense ceramics with translucency were obtained at considerably lower sintering temperatures.

• Korean Journal of Materials Research
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• v.17 no.9
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• pp.480-483
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• 2007

Hydroxyapatites were prepared by the different $SiO_2$ addition at $1450^{\circ}C$ for 2h. With the increase of $SiO_2$ addition, microstructure, bulk density, porosity, mechanical strength of $hydroxyapatite/{\beta}-TCP$ composite were investigated. When the sintered HAp contained 1 wt% $SiO_2$, the each properties of the HAp were increased. But the excess addition of $SiO_2$ content above 1wt% the each property were decreased. This results were due to the ${\beta}-TCP$ phase. The ${\beta}-TCP$ phase appeared at 3 wt% $SiO_2$ addition and the ${\beta}-TCP$ phase was enhanced by the $SiO_2$ increasing.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.4
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• pp.143-149
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• 2020

Calcium phosphates recognized as important bio-materials have been successfully synthesized by simple precipitation using waste abalone shells, which are rich mineral sources of calcium. Calcium hydroxide (Ca(OH)₂) originated from abalone shells was used as calcium source (precursor) for the preparation. Synthesis of calcium phosphates was performed by reacting calcium hydroxide with phosphoric acid (H₃PO₄) in aqueous solution. The initial precursor Ca/P ratios were adjusted to 1.50, 1.59 and 1.67, and the effect of the composition and the heat treatment on the synthesized powders and sintered bodies was investigated. The phases of the sintered ceramics prepared at 1150℃ were hydroxyapatite (HAp), β-tricalcium phosphate (β-TCP), and biphasic phosphate (HAp with β-TCP)), which were determined by the initial precursor Ca/P ratios. The results demonstrate the possibility for the synthesis of high value-added calcium phosphates from economical starting materials with low cost and high availability.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.14.1-14.6
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• 2016

Background: In guided bone regeneration (GBR) technique, many materials have been used for improving biological effectiveness by adding on membranes. The new membrane which was constructed with chitin-fibroin-hydroxyapatite (CNF/HAP) was compared with a collagen membrane (Bio-$Gide^{(R)}$) by means of micro-computed tomography. Methods: Fifty-four rats were used in this study. A critical-sized (8 mm) bony defect was created in the calvaria with a trephine bur. The CNF/HAP membrane was prepared by thermally induced phase separation. In the experimental group (n = 18), the CNF/HAP membrane was used to cover the bony defect, and in the control group (n = 18), a resorbable collagen membrane (Bio-$Gide^{(R)}$) was used. In the negative control group (n = 18), no membrane was used. In each group, six animals were euthanized at 2, 4, and 8 weeks after surgery. The specimens were analyzed using micro-CT. Results: Bone volume (BV) and bone mineral density (BMD) of the new bone showed significant difference between the negative control group and membrane groups (P < 0.05). However, between two membranes, the difference was not significant. Conclusions: The CNF/HAP membrane has significant effect on the new bone formation and has the potential to be applied for guided bone regeneration.