• The Korean Journal of Ceramics
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• 제7권1호
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• pp.41-44
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• 2001

A composite of $Ca_3$(PO$_4$)$_2$ and MgAl$_2$O$_4$ spinel is biologically active and has enduring strength. Its strength depends on the spinel phase. The flaws in the spinel depend on the grain size of the calcium phosphate phase and are not altered by dissolution. The calcium phosphate, ${\alpha}$ tri-calcium phosphate, controls the tissue response. Bone bonds to the implant. A design for a bone graft as a replacement for a section of the diaphysis of a canine femur provides for tensile, compressive, torsional and bending load; and for the physiological processes of bonding and remodeling. A bone plate, used to stabilize the implant at time of surgery was removed after about one year. Over seven years of service have been achieved without internal or external fixation.

• Asian-Australasian Journal of Animal Sciences
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• 제6권4호
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• pp.581-589
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• 1993

A plasmid vector, $RSVLTR/{\beta}G2$, containing lacZ gene under the control of the RSVLTR promoter were transfected into chicken embryo fibroblasts by three different transfection methods. Calcium phosphate, lipsome and DEAE-dextran techniques were applied for transfection of chicken cells. A histochemical assay with X-gal was used as a simple method for screening transfected cells. Plasmid $RSVLTR/{\beta}G2$ was expressed proficiently in the chicken embryo fibroblast. Calcium phosphate-DNA precipitate transfection resulted in the highest efficiency for transient expression of $RSVLTR/{\beta}G2$. Transfected cells formed colonies on the 9th day of incubation indicating stable transformation of the inserted plasmid.

• 한국세라믹학회지
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• 제50권4호
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• pp.257-262
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• 2013

A biomimetic approach was applied for the chemical deposition of calcium phosphate (CaP) coatings on 3 mole% yttrium-stabilized zirconia [3YSZ] powders. The solid-state reaction of 3YSZ powders with the addition of CaP was investigated for the development of biodegradable zirconia ceramics. The solid-state interaction between the 3YSZ matrix powders and the CaP additives differed from the behavior of commercial zirconia matrix powders. The 3YSZ powders were chemically reacted with precursors for the CaP formation. 3YSZ powders were mixed in an aqueous solution of Ca-P precursors and the CaP was precipitated on the surface of the 3YSZ matrix powders. The CaP-doped YSZ powders were calcined at $1100^{\circ}C$ and shaped powder blocks were then fired at $1600^{\circ}C$ for 2 h. The CaP phase formation was investigated using FE-SEM and XRD analysis.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권2호
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• pp.32-40
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• 2015

Laboratory column experiments were conducted to evaluate the feasibility of injectable apatite method for the sequestration of Sr-90 in groundwater. The columns were tested to evaluate the rate of citrate biodegradation, the amounts of apatite formed, and the treatability of strontium by the sediment and apatite. The results showed the decreases in citrate, calcium, and phosphate concentrations and the increases in alkalinity and citrate degradation products (acetate and formate) in the columns, suggesting that the citrate degradation and formation of calcium phosphate are occurring. Although the calcium and phosphate were not completely consumed within the columns, some amounts of apatite were formed and it showed an ability to treat strontium in groundwater. This study provides a fundamental understanding of reaction mechanisms for the injectable apatite sequestration method for Sr-90 removal.

• 대한치과보존학회:학술대회논문집
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• 대한치과보존학회 2003년도 제120회 추계학술대회 제 5차 한ㆍ일 치과보존학회 공동학술대회
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• pp.592-593
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• 2003

I. Objectives The purpose of this study was to compare in vivo the biocompatibility of new calcium phosphate-based root canal sealers(CAPSEAL I, CAPSEAL II) with another type of commercially available calcium phosphate sealer (Apatite Root Sealer type I, Apatite Root Sealer type II) and zinc oxide-eugenol-based sealer (Pulp Canal Sealer EWT) after implantaion in rat subcutaneous tissue. II. Materials and Methods 64 Sprague-Dawley rats were used. There were five groups of three animals each for experimental period of 1, 2, 4, and 12 weeks. The teflon tubes, 5mm in length with an inner diameter of 1.5mm, were washed with ethanol and distilled weter and autoclaved.(omitted)

• Clinical and Experimental Pediatrics
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• 제50권3호
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• pp.230-235
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• 2007

In the early neonatal period, the neonate is challenged by the loss of the placental calcium transport and manifests a quick transition, from an environment in which PTHrP plays an important role to a PTH- and 1,25-dihydroxyvitamin D-controlled neonatal milieu. Disturbances in mineral homeostasis are common in the neonatal period, especially in premature infants and infants who are hospitalized in an intensive care unit. In many cases these disturbances are thought to be exaggerated responses to the normal physiological transition from the intrauterine environment to neonatal independence. Some disturbances in calcium and phosphate homeostasis are the result of genetic defects, which in many instances can now be identified at the molecular level. Although fetus develop remarkably normally in the presence of maternal calcium, PTH and vitamin D deficiency, the neonates demonstrate abnormalities that are consequences of the prior abnormal maternal calcium homeostasis. Evaluation and management of hypocalcemia and hypercalcemia in neonate requires specific knowledge of perinatal mineral physiology and the unique clinical and biochemical features of newborn mineral metabolism.

• Journal of Periodontal and Implant Science
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• 제38권sup2호
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• pp.273-298
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• 2008

Purpose: The aim of this review is to introduce a novel bone-graft material for hard-tissue regeneration based on the calcium phosphate glass(CPG). Materials and Methods: CPG was synthesized by melting and subsequent quenching process in the system of CaO-$CaF_2-P_2O_5$-MgO-ZnO having a much lower Ca/P ratio than that of conventional calcium phosphates such as HA or TCP. The biodegradability and bioactivity were performed. Effects on the proliferation, calcification and mineralization of osteoblast-like cells were examined in vitro. Influence in new bone and cementum formations was investigated in vivo using calvarial defects of Sprague-Dawley rats as well as 1-wall intrabony defect of beagle dogs. The application to the tissue-engineered macroporous scaffold and in vitro and in vivo tests was explored. Results: The extent of dissolution decreased with increasing Ca/P ratio. Exposure to either simulated body fluid or fetal bovine serum caused precipitation on the surface. The calcification and mineralization of osteoblast-like cells were enhanced by CPG. CPG promoted new bone and cementum formation in the calvarial defect of Sprague-Dawley rats after 8 weeks. The macroporous scaffolds can be fabricated with $500{\sim}800{\mu}m$ of pore size and a three-dimensionally interconnected open pore system. The stem cells were seeded continuously proliferated in CPG scaffold. Extracellular matrix and the osteocalcin were observed at the $2^{nd}$ days and $4^{th}$ week. A significant difference in new bone and cementum formations was observed in vivo (p<0.05). Conclusion: The novel calcium phosphate glass may play an integral role as potential biomaterial for regeneration of new bone and cementum.

• 한국재료학회지
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• 제17권8호
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• pp.408-413
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• 2007

Process of the hydroxyapapite(HA) precipitation on bioactive titanium metal prepared by NaOH in a modified-simulated body fluid(mSBF) was investigated by high resolution transmission electron microscope (HRTEM) attached with energy dispersive X-ray spectrometer(EDX). The amorphous titanate phase on titanium surface is form by NaOH treatment and an amorphous titanate incorporated calcium and phosphate ions in the liquid to form an amorphous calcium phosphate. With increasing of soaking time in the liquid, the HA particles are observed in amorphous calcium phosphate phase with a Ca/P atomic ratio of I.30. The octacalcium phosphate (OCP) structure is not detected in HRTEM image and electron diffraction pattern. After a long soaking time, the HA particles grow as needle-like shape on titanium surface and a large particle-like aggregates of needle-like substance were observed to form on titanium surface within needle-like shape. A long axis of needle parallels to c-direction of the hexagonal HA structure.

• 한국세라믹학회지
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• 제53권6호
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• pp.670-675
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• 2016

Calcium phosphate crystallites were prepared by wet chemical method for use in artificial bone. In order to obtain ${\beta}$-tricalcium phosphate (TCP), nano-crystalline calcium phosphate (CaP) was precipitated at $37^{\circ}C$ and at $pH5.0{\pm}0.1$ under stirring using highly active $Ca(OH)_2$ in DI water and an aqueous solution of $H_3PO_4$. The precipitated nano-crystalline CaP solution was kept at $90^{\circ}C$ for the growth of CaP crystallites. Through the growing process of CaP crystallites, we were able to obtain various sizes of rectangular CaP crystallites according to the crystal growing times. Dry nano-crystalline CaP powders at $37^{\circ}C$ were mixed with dry macro-crystalline CaP crystallites and the shaped mixture sample was fired at $1150^{\circ}C$ to make a ${\beta}-TCP$ block. Several tens of nm powders were uniformly coated on the surface, which was comprised of powders of several tens of ${\mu}m$, using a vibrator. The mixing ratio between the nanometer powders and the micrometer powders greatly affected the mechanical strength of the mixture block; the most appropriate ratio of these two materials was 50 wt% to 50 wt%. The sintered block showed improved mechanical strength, which was caused by the solid state interaction between the nano-crystalline ${\beta}-TCP$ and the macro-crystalline ${\beta}-TCP$.

• 한국결정성장학회지
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• 제20권2호
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• pp.93-100
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• 2010

X-선 회절 분석방법을 통해 biphasic calcium phosphate(BCP) 분말의 Ca/P 몰 비율을 확인하고 특성을 평가하였다. 다양한 화학 양론적인 Ca/P 몰 비율을 가지는 BCP 분말은 공침반응 및 하소과정을 통해 합성하였다. 1.5에서 1.67의 Ca/P 몰 비율을 가지는 분말의 조성은 초기 출발물질의 Ca/P 몰 비율, pH 10에서의 공침 과정 및$900^{\circ}C$ 열처리에 의해 정해졌다. 화학 양론적 Ca/P 몰 비율을 가지는 BCP 분말의 구조, 형상 및 화학적 특성평가는 XRD의 상-정량 확인 분석을 바탕으로 주사전자현미경 및 유도 결합 플라즈마 분광분석기와 함께 수행 하였다. BCP 분말의 용해도는 $36.5^{\circ}C$ 및 pH 7.4 의 phosphate buffer solution(PBS)에서 특성평가 하였다.