• Applied Chemistry for Engineering
• /
• v.27 no.5
• /
• pp.543-545
• /
• 2016

Four different hydroxyapatites (HAP) were prepared by a solvothermal method under different pHs and solvent species. The synthesized hydroxyapatites were analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Four HAPs exhibited similar XRD patterns regardless of synthetic conditions. However, the morphology of hydroxyapatites was dependent of pH and solvent species under synthetic condition. The HAP prepared in pH 12 showed an elongated shape along the [001] direction compared to that prepared in pH 8. Also, the morphology of the HAPs synthesized in the presence of methanol and ethanol exhibited the more elongated hexagonal rod shape along the [001] direction with the high aspect ratio.

• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.04a
• /
• pp.56.1-56
• /
• 2003

• The Journal of Korean Academy of Prosthodontics
• /
• v.27 no.1
• /
• pp.181-192
• /
• 1989

Loss of teeth causes the inevitable reduction of residual ridge. Among the various methods solving this problem, hydroxyapatite proved to be useful for correction of ridge defect and irregularity. The purpose of this study is to evaluate the tissue responses of two types Of hydroxyapatites and resin polymer. Calcitite 2040 (Calcitek Inc.), Interpore 200 (Interpore Int.), and HTR polymer (HTR Sciences) were implanted into the jaw of an adult dog. The procedure was designed to obtain the results of 1 week, 2 week, 4 week, and 12 week-intervals. And after 12 weeks from the first operation day, the dog was sacrificed and evaluated histologically by light microscope. The results were as follows : 1. The mucosa was healed after two weeks. 2. After 1 week, there were acute inflammatory cells, but diminished after 2 weeks and were not seen after 12 weeks. 3. The hydroxyapatites implanted in soft tissues were surrounded by fibrous connective tissue. And some foreign body giant cells were found. 4. Calcitite and Interpore particles implanted subperiosteally were surrounded by newly formed bone after 12 months. And direct contact between bone and particles was noted. 5. The HTR particles implanted in soft tissues were encapsulated by fibrous connective tissues. The sample where the particles contacted directly to bone could not obtained by some probable insufficiencies of surgical technique or care of the animal. And the residue of HTR particles was digested by macrophage.

• Economic and Environmental Geology
• /
• v.28 no.3
• /
• pp.231-241
• /
• 1995

It is well known that hydroxyapatite [$Ca_{10}(PO_4)_6(OH)_2$] have an exchangeability for various heavy metal ions in aqueous solution. To evalute the feasibility of employing the synthetic hydroxyapatites as an eliminatable exchanger for environmentally noxious caions in waste water, the adsorption properties, the removal capacities and the selectivity of the apatites for various cations were investigated in more detailed. The heavy metal cations have been exchanged in calcium part of hydroxyapatite. The order of the degree of amount exchanged of the investigated cations is $Pb^{2+}>Cd^{2+}>Zn^{2+}>Ba^{2+}$. The molar ratios between released $Cd^{2+}$ ions and remeved divalent metal cations in the reacted solution with hydroxyapatite are roughly close to an integer 1.0, suggesting that an ion-exchange reaction could have played a major role in the removal of heavy metals rather then an adsorption effect. The exchangeability of the hydroxyapatite powder of Ca/P molar ratio 1.67, which have specipic surface area of $104.5m^2g^{-1}$, appeared to be better then $237.6{\mu}g$ per g for $Pb^{2+}$ ions. The removal capacity of the heavy metal ions varies directly as particle size of hydroxyapatites. All evidences obtained indicate that the synthesized hydroxyapatite powders by precipitation reaction method can be employed as an effective cation exchanger for eliminating noxious ions in waste water even in some improvemental.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.35 no.1
• /
• pp.13-17
• /
• 2013

Purpose: This study evaluated the capability of bone formation of silk fibroin particles coated with hydroxyapatites (HA/SF), as bone graft material when put into the calvarial defect of rats. Methods: Twenty Sprague Dawley rats were used for this study and round shaped defects were formed in the center of parietal bones (diameter: 8.0 mm). The defect was filled with (1) HA/SF (experimental group), or (2) left as a vacant space (control group). The animals were sacrificed at 4 or 8 weeks, postoperatively. The specimens were decalcified and stained with Masson's trichrome for histomorphometric analysis. Results: The average of new bone formation was $33.18{\pm}3.10%$ in the experimental group and $20.49{\pm}5.79%$ in the control group at 4 weeks postoperatively. That was $42.52{\pm}7.74%$ in the experimental group and $25.50{\pm}7.31%$ in the control group at 8 weeks postoperatively. The difference between the groups was significantly higher at both 4 weeks and 8 weeks postoperatively (P<0.05). Conclusion: The rat calvarial defect was successfully repaired by HA/SF graft. The HA/SF graft showed more new bone formation compared with the unfilled control.

• Journal of Yeungnam Medical Science
• /
• v.37 no.3
• /
• pp.169-178
• /
• 2020

Glass ionomer cement (GIC) is a tailor-made material that is used as a filling material in dentistry. GIC is cured by an acid-base reaction consisting of a glass filler and ionic polymers. When the glass filler and ionic polymers are mixed, ionic bonds of the material itself are formed. In addition, the extra polymer anion reacts with calcium in enamel or dentin to increase adhesion to the tooth tissue. GICs are widely used as adhesives for artificial crowns or orthodontic brackets, and are also used as tooth repair material, cavity liner, and filling materials. In this review, the current status of GIC research and development and its prospects for the future have been discussed in detail.

• Journal of the Korean Ceramic Society
• /
• v.26 no.2
• /
• pp.147-156
• /
• 1989

The effects of starting composition, sintering temperature and porosity on the mechanical properties of hydroxyapatite ceramics were investigated. The hydroxyapatite powder were prepared by precipitation method using Ca(NO3)2.4H2O and (NH4)2.HPO4. The obtained powders were Ca-deficient hydroxyapatites and as the Ca/P mole ration in the initial solution was increased, the particle size of the precipitates was decreased, and the decomposition of hydroxyapatite to $\beta$-TCP was controlled. The porosity, as well as Ca/P mole ratio in starting composition and sintering temperature, plays major role in the mechanical properties of dense hydroxyapatite ceramics.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.23 no.4
• /
• pp.931-936
• /
• 1996

Many kinds of soluble calcium salts such as calcium lactate are known to reduce the enamel demineralization. In this study, calcium lactate was tested for its effect on the demineralization process of hydroxyapatite. Synthetic hydroxyapatites were used as a standardized material instead of human enamel which is rarely heterogenous. And, for the purpose of hydroxyapatite demineralization, lactic acid was used. By comparing the weight of hydroxyapatite pre-demineralization and post-demineralization, it was possible to examine the effect of calcium lactate on demineralization. The weight of demineralized hydroxyapatite was reduced by about 46% and 59% with 20mM and 40mM calcium lactate, respectively. In conclusion, low concentrations of calcium lactate showed an inhibitory effect on the demineralization of synthetic hydroxyapatite.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.1
• /
• pp.221-224
• /
• 2013

Three different kinds of hydroxyapatites (HAPs) having different sizes and compositions are prepared by hydrothermal and molten salt syntheses. Using the ion exchange reactions, ruthenium ions are incorporated on the surface of HAPs. The crystallinity, morphology and ruthenium contents are investigated by XRD, SEM, TEM and ICP. We found that smaller size of HAP having large amounts of ruthenium under ion exchange reaction shows higher catalytic activity for aerobic oxidation of alcohols.

• Journal of Powder Materials
• /
• v.12 no.6 s.53
• /
• pp.428-432
• /
• 2005

In the present study, silver-doped antibacterial hydroxyapatites were successfully prepared by the sol-gel method. For the starting solution, the molar ratio of $Ca(NO_3)_2{\cdot}4H_2O, P(OC_2H_5)_3,\;C_2H_5OH,\;and\;H_O$ was set to 0.075:0.045:20:0.135; $AgNO_3$ was added to a ratio of Ag to total cation concentration of $0.5-12 mol\%$. The prepared sol was dried at $100^{\circ}C$ for 48h and heat-treated at $1000^{\circ}C$ for 2h to obtain particles in the 200-500nm size range. The product from the synthesis of silver-doped hydroxyapatite was investigated through X-ray diffraction experiments and scanning electron microscopy. The product showed high antibacterial properties, with a disinfection ratio of Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC 25922) over $99.9^{\circ}C$ as calculated from an antimicrobial effects evaluation by the shake flask method.