• The Journal of Korean Academy of Prosthodontics
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• v.42 no.5
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• pp.556-571
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• 2004

Statement of problem: Surface texture of the implant is one of the important factors of the implant success, especially in the immediate implant loading. Many methods of the surface treatment of implant have developed and introduced. Purpose : This study was to evaluate the effects of the Ca-P coating implant crystallized the hydroxyapatite on the surface by the removal torque test and the histomorphometric analysis in vivo. Material and methods: 135 screw type implants, 4.0mm in length and 3.75mm in diameter were used in this study. Implants were divided into 3 groups and treated in the different mothods. Group I was not treated, Group II was treated in the SLA method, and Group III was treated in the Ca-P coating with the anodizing method and the hydroxyapatite was crystallized on the surface with the hydrothermal treatment. Firstly, the surface roughness of each group was measured, 45 rabbits were used in this experiment. Two implants were inserted on right tibial metaphysis and one implant was inserted on left side with the alternating order. After the healing periods of 3, 5, and 12 weeks, the rabbits were sacrificed to evaluate the osseointergration by the removal torque test and the histomorphometric analysis. Results : 1. In the analysis for the surface roughness, Group II showed the highest roughness. And Group III showed higher secondly. There was a significant difference one another statistically 2. In the removal torque test, Group III and II were significantly higher than Group I. There was no statistical difference between Group III and Group II. 3. For all Groups, the removal torque values at 12th week were significantly higher than at 3rd and 5th week. 4. In histomorphometric analysis, the bone implant contact rates of Group III and II were higher than that of Group I at 3rd and 5th week. There was a significant difference at 5th week. 5. In histomorphometric analysis, the bone implant contact rate of Group III and II increased from 3rd week to 5th week, but decreased at 12th week. In Group I, the contact rate at 12th week was significantly higher than at 3rd week and 5th week.

• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.145-151
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• 2021

This study aimed to investigate the efficient conduct of HA coating on Ti Gr4 for the practical use of medical device. Ti Gr4 alloy specimens measuring 𝜱 25mm × 1mm were sprayed with hydroxyapatite using thermal spray according to ASTM F1185-88. The surface was evaluated at #120, #400, #1,000 sandpaper and barrel finishing. Each coating properties was analyzed using SEM, UTS 20,000psi cap. and in vitro cytotoxicity. Surface morphology consists of well molten particles with very little resolidified or unmolten areas. The average Ca/P ratio is 1.74 which is in good agreement with theoretical value of 1.67. The average roughness Ra is very representative of roughness of specimen. The coatings are dense and well adhered to the substrate. The average bond strength was 61.74 MPa with a standard deviation of 4.06 which indicates fairly reliable results for ASTM 633 type tests. Variations in results from jig design, epoxy used, crosshead speeds etc. in vitro cytotoxicity result had a Grade 3. The results of the study are expected to be helpful in osseointegration and plasma-spray HA coated Ti Gr4 are more satisfactory in HA coating thickness elevation which is preferable to any other system.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.133-136
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• 1996

We investigated how hydroxyapatite (HA) coating onto a porous super stainless steel (S.S.S, 22Cr-20Ni-6Mo-0.25N) affects bone ingrowth in a dog transcortical femoral model. Implants were histologically evaluated after 4 and 48 weeks of implantation, and the bone bonding strength at the bone/implant interface was examined by employing the pull-out test. The direct osseous tissue bonding onto the HA-coated S.S.S was observed, but the uncoated stainless steels had thin fibrous tissue layers. The mean interface strength of the HA-coated S.S.S was 1.5 and 2.5 times greater than those of the S.S.S and the 316L SS after one year of implantation, respectively. In preliminary studies, no toxic responce was observed from a cytotoxicity test of the S.S.S, having similar corrosion resistance to titanium. Our results suggest that early osteoconductive nature of HA coating may induce long term osteointegration for a bioinert substrate.

• Korean Journal of Metals and Materials
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• v.50 no.5
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• pp.395-400
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• 2012

In this study, we have investigated the surface morphology of hydroxyapatite (HA) coated Ti alloy surface using pulsed laser plating. The HA (tooth ash) films were grown by pulsed KrF excimer laser, film surfaces were analyzed for topology, chemical composition, crystal structure and electrochemical behavior. The Ti-6Al-4V alloy showed ${\alpha}$ and ${\beta}$ phase, Cp-Ti showed ${\alpha}$ phase and the HA coated surface showed HA and Ti alloy peaks. The HA coating layer was formed with $1-2{\mu}m$ droplets and grain-like particles, particles which were smaller than the HA target particle, and the composition of the HA coatings were composed of Ca and P. From the electrochemical test, the pitting potential (1580 mV) of HA coated Ti-6Al-4V alloy was higher than those of Cp-Ti (1060 mV) and HA coated Cp-Ti (1350 mV). The HA coated samples showed a lower current density than non-HA coated samples, whereas, the polarization resistance of HA coated samples showed a high value compared to non-HA coated samples.

• Journal of the Korean Chemical Society
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• v.57 no.4
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• pp.493-498
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• 2013

Liposomes, which can deliver payload at target site, have been studied as drug carrier. However, conventional liposomes have limitation for drug release at target site. Therefore, we developed hydroxyapatite (HA) coated ultrasound sensitive liposomes to increase drug release at target site and to enhance stability in blood stream. Control liposome was prepared using hydrogenated soy phosphatidylcholine (HSPC) and cholesterol, and then we assessed HA coating on the surface of control liposomes using calcium acetate, phosphoric acid, and 25% ammonium solution. Doxorubicin was used as a model drug. Size of HA coated liposomes was 120 nm and encapsulation efficiency of doxorubicin in liposomes was up to 95%. Size of HA coated liposomes are not changed in 30% serum solution, however, the control liposomes was 1.4 fold increased. After ultrasound triggered drug release from liposomes, intracellular efficiency of drug released from HA coated liposomes was 3 fold increased compared to control liposomes. In this study, we developed ultrasound sensitive liposomes to enhance drug release, which will be applied in controlled drug release at disease site.

• Journal of Periodontal and Implant Science
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• v.23 no.3
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• pp.400-410
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• 1993

Dental implants have been widely used in the treatment of esthetic and functional problems of the mouth due to alveolar bone loss, after tooth extraction. The success of implantation strongly depends on osseointegration. For osseointegration, implant material, methodology, and design have been investigated. For materials, two popular materials at present are titanium and hydroxyapatite. For methods, immediate implantation is being used recently. The purpose of this study is to evaluate osseointegration between the unthreaded cylindrical TPS implant and the HA-coated implant by a histomorphometric analysis. For this analysis, experimental periodontits was induced on the 3, 4 premolars of adult dogs by the ligation of orthodontic threads. Thereafter, each tooth was extracted. TPS. Implants and HA-coated implants were immediately inserted in the extraction socket. In control group, TPS implants were immediately inserted, and In experimental group, HA implants were immediately inserted. The dogs were sacrificed after 12 weeks, then the specimens were prepared for LM and histomorphometric analysis. The conclusion of this study is as follows l. In both control and experimental group, no inflammatory cells were observed. 2. The results of the histomorphometric analysis showed that the total osseointegration was 48.5% in control group, and 68.8% in expermental group. The experimental group was higher than the control group, and the difference was not statistically significant (p<0.05). 3. The results of the histomorphometric analysis showed that the osseointegration in the hole was 40.6% in control group, and 70.2% in experimental group. The experimental group was higher than the control group, and the difference was statistically significant (p<0.05). In both control and experinental group, no inflammatory cells were observed. 4. The results of the histomorphometric analysis showed that the osseointegration in the lower part was 52.1% in control group, and 73.3% in experimental group. The experimental group was higher than the control group, and the difference was statistically significant (p<0.05). 5. In experimental group, the bone to HA interface seemed to be mixed of bone and HA. We could not distinguish HA from the bone. The HA coating was detached from the titanium surface.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.162-163
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• 2009

마이크로플라즈마 스프레이(Microplasma spray, MPS)를 이용하여 hydroxyapatite(HA) 코팅을 수행하여, HA코팅 층에 대한 밀착력을 측정하였다. 밀착력의 측정은 ASTM C633에 의거하였으며, 실험의 설계는 다꾸치법 (L18($2^{1}3^{7}$))을 이용하였다. 본 실험에서 HA코팅 층과 모재에 대한 밀착력 측정에서 35.8MPa의 밀착력을 얻었으며, SEM을 이용하여, 표면 형상과 밀착력 실험 후의 파단면을 관찰하였다. 또한, 나노 인덴테이션을 사용하여, 탄성계수와 미소경도를 측정하였다.

• 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.

• Korean Journal of Materials Research
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• v.21 no.7
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• pp.384-390
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• 2011

Ti-6Al-4V ELI (Extra Low Interstitial) alloy has been widely used as an alternative to bone due to its excellent biocompatibility. However, it still has many problems, including a high elastic modulus and toxicity. Therefore, nontoxic biomaterials with a low elastic modulus should be developed. However, the fabrication of a uniform coating is challenging. Moreover, the coating layer on Ti and Ti alloy substrates can be peeled off after implantation. To overcome these problems, it is necessary to produce bulk Ti and Ti alloy with hydroxyapatite (HA) composites. In this study, Ti, Nb, and Zr powders, which are biocompatible elements, were milled in a mixing machine (24h) and by planetary mechanical ball milling (1h, 4h, and 6h), respectively. Ti-35%Nb-7%Zr and Ti-35%Nb-7%Zr-10%HA composites were fabricated by spark plasma sintering (SPS) at $1000^{\circ}C$ under 70MPa using mixed and milled powders. The effects of HA addition and milling time on the biocompatibility and physical and mechanical properties of the Ti-35%Nb-7%Zr-(10%HA) alloys have been investigated. $Ti_2O$, CaO, $CaTiO_3$, and $Ti_xP_y$ phases were formed by chemical reaction during sintering. Vickers hardness of the sintered composites increases with increased milling time and by the addition of HA. The biocompatibilty of the HA added Ti-Nb-Zr alloys was improved, but the sintering ability was decreased.

• Journal of Periodontal and Implant Science
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• v.33 no.1
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• pp.1-11
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• 2003

Hydroxyapatite(HA) has been extensively used as bone graft materials and tooth implant surface coating materials because of its biocompatibility and osteoconductive properties. However, as HA is intrinsically poor in mechanical properties, zirconia($ZrO_2$) was incorporated with HA as reinforcing phases for improvement of mechanical properties. The purpose of this study was to investigate the biological activities of HA-coated zirconia through the cell proliferation test, measurements of alkaline phosphatase activity, and histologic examination. Four kinds of tested blocks were prepared according to the pore size (300-500${\mu}m$/500-700${\mu}m$) and the porosity (70%/90%). Cell proliferation and alkaline phosphatase activity was measured at 1, 7, 14 days. The number of cells proliferate after 7, 14 days were significantly increased in all groups when compared with that of the first day, but there was no significant difference between the 4 groups at each time period. At the 7 day, alkaline phosphatase activities of cells cultured in 4 groups were higher than that of the first day, but there was no significant difference between the 4 groups at each time period. The human gingival fibroblast and MG 63 cell was used to evaluate the cell cytotoxicity using MTT test. The materials tested in the current study turned out to be non-cytotoxic. In histologic examination(SEM), at 1 day there were many cells attached on the surfaces of all kinds of tested blocks. The number of cells were increased over time. At the 14 day, there were more cells proliferated than 1 day and some of the pores of blocks were partially filled with the proliferated cells. The in vitro response of osteoblast-like cells to the HA-coated zirconia showed comparable effect on transformation comparable to hydroxyapatite.