• 한국분말재료학회지
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• 제19권6호
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• pp.416-423
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• 2012

This paper introduces an effect of a preparing $ZrO_2$-Ag composite on its mechanical properties and microstructure. In present study, $ZrO_2$-Ag was prepared by reduction-deposition route and wetting dispersive milling method, respectively. Two type of Ag powders (nano Ag and micron Ag size, respectively) were dispersed into $ZrO_2$ powder during wetting dispersive milling in D.I. water. Each sample was sintered at $1450^{\circ}C$ for 2hr in atmosphere, and then several mechanical tests and analysis of microstructure were carried out by bending test, hardness, fracture toughness and fracture surface microstructure. As for microstructure, the Ag coated $ZrO_2$ showed homogeneously dispersed Ag in $ZrO_2$ in where pore defect did not appear. However, $ZrO_2$-nano Ag and $ZrO_2$-micro Ag composite appeared Ag aggregation and its pore defect, which carried out low mechanical property and wide error function value.

• 대한수의학회지
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• 제50권3호
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• pp.171-177
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• 2010

The purpose of this study was to evaluate the osteogenic capacity of water extract of danshen (Salvia miltiorrhiza Bunge). We have established in rat critical-sized calvarial defect model using the combination with collagen scaffold and danshen hydrophilic extract. All rats were extinguished at 8 weeks after bone graft surgery, and the bone regeneration ability of bone grafting sides was evaluated by plain radiography and micro-CT. These results revealed water extract of danshen had the potential to promote osteogenesis especially continuous oral administration with local treatment compared to one-shot local treatment. This compound may provide a new alternative agent for growth factors to promote bone healing and bone regeneration. In conclusion, these results suggest that danshen hydrophilic extract have the potential to promote osteogenesis in bone defects. Further studies about fusion technology with salvianolic acid B, peptides, growth factors, and scaffolds using of the combination of tissue engineering, cell engineering and mechanical engineering are needed.

• 소성∙가공
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• 제25권6호
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• pp.353-358
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• 2016

Direct energy deposition (DED) is an additive manufacturing technique that involves the melting of metal powder with a high-powered laser beam and is used to build a variety of components. In recent year, it can be widely used in order to produce hard, wear resistant and/or corrosion resistant surface layers of metallic mechanical parts, such as dies and molds. For the purpose of the hardfacing to achieve high wear resistance and hardness, application of high speed steel (HSS) can be expected to improve the tool life. During the DED process using the high-carbon steel, however, defects (delamination or cracking) can be induced by rapid solidification of the molten powder. Thus, substrate preheating is generally adopted to reduce the deposition defect. While the substrate preheating ensures defect-free deposition, it is important to select the optimal preheating temperature since it also affects the microstructure evolution and mechanical properties. In this study, AISI M4 powder was deposited on the AISI 1045 substrate preheated at different temperatures (room temperature to $500^{\circ}C$). In addition, the micro-hardness distribution, cooling rates, and microstructures of the deposited layers were investigated in order to observe the influence of the substrate preheating on the mechanical and metallurgical properties.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제42권
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• pp.18.1-18.9
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• 2020

Background: Bone grafting has been considered the gold standard for hard tissue reconstructive surgery and is widely used for large mandibular defect reconstruction. However, the midface encompasses delicate structures that are surrounded by a complex bone architecture, which makes bone grafting using traditional methods very challenging. Three-dimensional (3D) bioprinting is a developing technology that is derived from the evolution of additive manufacturing. It enables precise development of a scaffold from different available biomaterials that mimic the shape, size, and dimension of a defect without relying only on the surgeon's skills and capabilities, and subsequently, may enhance surgical outcomes and, in turn, patient satisfaction and quality of life. Review: This review summarizes different biomaterial classes that can be used in 3D bioprinters as bioinks to fabricate bone scaffolds, including polymers, bioceramics, and composites. It also describes the advantages and limitations of the three currently used 3D bioprinting technologies: inkjet bioprinting, micro-extrusion, and laserassisted bioprinting. Conclusions: Although 3D bioprinting technology is still in its infancy and requires further development and optimization both in biomaterials and techniques, it offers great promise and potential for facial reconstruction with improved outcome.

• Journal of Veterinary Science
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• 제24권6호
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• pp.79.1-79.16
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• 2023

Background: The need for a storage method capable of preserving the intrinsic properties of bones without using toxic substances has always been raised. Supercooling is a relatively recently introduced preservation method that meets this need. Supercooling refers to the phenomenon of liquid in which the temperature drops below its freezing point without solidifying or crystallizing. Objectives: The purpose of this study was to identify the preservation efficiency and applicability of the supercooling technique as a cortical bone allograft storage modality. Methods: The biomechanical effects of various storage methods, including deep freezing, cryopreservation, lyophilization, glycerol preservation, and supercooling, were evaluated with the three-point banding test, axial compression test, and electron microscopy. Additionally, cortical bone allografts were applied to the radial bone defect in New Zealand White rabbits to determine the biological effects. The degree of bone union was assessed with postoperative clinical signs, radiography, micro-computed tomography, and biomechanical analysis. Results: The biomechanical properties of cortical bone grafts preserved using glycerol and supercooling method were found to be comparable to those of normal bone while also significantly stronger than deep-frozen, cryopreserved, and lyophilized bone grafts. Preclinical research performed in rabbit radial defect models revealed that supercooled and glycerol-preserved bone allografts exhibited significantly better bone union than other groups. Conclusions: Considering the biomechanical and biological superiority, the supercooling technique could be one of the optimal preservation methods for cortical bone allografts. This study will form the basis for a novel application of supercooling as a bone material preservation technique.

• 한국방사선학회논문지
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• 제5권1호
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• pp.11-18
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• 2011

다능성 세포를 포함하는 골막은 골모세포와 연골세포로 분화될 수 있다. 그리고 배양된 골막유래세포는 골형성 능력을 가지고 있다. 이 연구의 목적은 골막유래 세포들과 골이식재 간의 상호작용을 평가하는 것이다. Sprague-Dawley 랫드의 두개골 골막에서 세포를 분리한 다음, 배양된 골막유래세포를 beta-tricalcium phosphate (${\beta}$-TCP)와 함께 임계결손부 크기의 두개결손부에 이식하였다. 모든 랫드는 골이식 수술 후 8주째에 희생되었으며, 골이식부의 골형성 능력은 일반방사선, micro CT 및 조직검사를 통해 평가되었다. ${\beta}$-TCP와 함께 이식된 골막유래세포는 골결손부에서 더욱 증가된 석회화작용을 나타내었으며, 골결손부 안쪽 및 가장자리에 골밀도 증가와 신생골이 형성되었다. 특히 골막유래세포는 ${\beta}$-TCP만 단독으로 이식하였을때보다 함께 이식 시 효과적으로 신생골을 형성하였다. 이러한 결과는 배양된 골막유래세포가 골결손부에서 골형성을 증진시킬 수 있는 가능성을 보였다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권5호
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• pp.293-298
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• 2012

Purpose: The aim of this study was to evaluate the bone regeneration ability of 1% tetracycline (TC)-loaded silk fibroin membrane (SFM), in a rabbit calvarial defect model. Methods: Twenty New Zealand white rabbits were used for this study. Bilateral round defects were made on the rabbit parietal bone, using trephine bur with an 8 mm diameter. TC-loaded SFM or SFM was covered on the right parietal bone defect, and the left parietal bone defects were uncovered for the control. The animals were humanely sacrificed at 4 or 8 weeks postoperatively. A micro-computerized tomography (${\mu}$-CT) of each specimen was taken for analysis of bone regeneration. Hematoxylin and Eosin stain were done to observe histological findings. Results: From the ${\mu}$-CT results, regenerated bone volume ($mm^3$) of 1% TC-loaded SFM, SFM, and control were $7.80{\pm}5.87$, $8.79{\pm}3.44$, and $10.61{\pm}5.3$ at 4 weeks postoperatively, respectively (P>0.05). Regenerated bone volume ($mm^3$) of 1% TC-loaded SFM, SFM, and control were $36.56{\pm}8.50$, $25.86{\pm}8.17$, and $19.09{\pm}5.07$ at 8 weeks postoperatively, respectively (P<0.05). Conclusion: The 1% TC-loaded SFM showed more bone regeneration than the SFM and the uncovered control, in guided bone regeneration.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제36권4호
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• pp.250-254
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• 2010

Introduction: This study evaluated the bone regenerative effect of silk fibroin mixed with platelet-rich fibrin (PRF) of a bone defect in rabbits. Materials and Methods: Ten New Zealand white rabbits were used for this study and bilateral round shaped defects were formed in the parietal bone (diameter: 8.0 mm). The silk fibroin mixed with PRF was grafted into the right parietal bone (experimental group). The left side (control group) was grafted only PRF. The animals were sacrificed at 4 weeks and 8 weeks. A micro-computerized tomography (${\mu}$CT) of each specimen was taken. Subsequently, the specimens were decalcified and stained for histological analysis. Results: The average value of plane film analysis was higher in the experimental group than in the control group at 4 weeks and 8weeks after surgery. However, the difference was not statistically significant.(P>0.05) The tissue mineral density (TMD) in the experimental group at 4 weeks after surgery was significantly higher than the control group.(P<0.05) Conclusion: Silk fibroin can be used as a scaffold of PRF for rabbit calvarial defect repair.

• Archives of Reconstructive Microsurgery
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• 제22권1호
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• pp.18-23
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• 2013

Purpose: For reconstruction of lower extremity defects, various flaps can be used and the appropriate flap must be selected and applied according to the size of the defect. In particular, in cases where the defect size is small to moderate, thinner or smaller volume flaps are useful. The authors performed reconstruction of small to moderate defects on the lower extremities using superficial circumflex iliac artery perforator free flaps and are reporting the results. Materials and Methods: Fifteen patients underwent reconstruction of defects on lower extremity areas using superficial circumflex iliac artery perforator free flaps from July 2011 to July 2012 at this hospital. The flaps were elevated from above the deep fat layer, and, in all cases, the vessel diameter of the flaps was less than 1mm, with the exception of superficial vein that accompanied it. Results: The mean follow up period was 4.46 months, and, despite a partial loss in the flap in two cases, there were no total losses. All donor sites were closed with primary closure, and there was no occurrence of complications, such as hematomas, seromas, or lymphorrheas. The patients were highly satisfied with the donor site scar since it could be masked by underwear. Conclusion: Compared to other flaps, superficial circumflex iliac artery perforator free flaps are thinner in thickness and smaller in volume, which results in a more natural contour of the recipient site after the operation. In addition, since the flap can be elevated from supra-deep fat layer, the operation time can be shortened, and lymphorrhea can be prevented, which in turn lessens donor-site morbidity.

• The Journal of Advanced Prosthodontics
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• 제2권1호
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• pp.7-13
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• 2010

Although most researchers agree that platelet-rich plasma (PRP) is a good source of autogenous growth factors, its effect on bone regeneration is still controversial. The purpose of this study was to evaluate whether increasing angiogenic factors in the human PRP to enhance new bone formation through rapid angiogenesis. MATERIAL AND METHODS. In vitro, the human platelets were activated with application of shear stress, $20\;{\mu}g/ml$ collagen, 2 mM $CaCl_2$ and 10U thrombin/$1\;{\times}\;10^9$ platelets. Level of vascular endothelial growth factor (VEGF) and platelet microparticle (PMP) in the activated platelets were checked. In the animal study, human angiogenic factors-enriched PRP was tested in 28 athymic rat's cranial critical bone defects with $\beta$-TCP. Angiogenesis and osteogenesis were evaluated by laser Doppler perfusion imaging, histology, dual energy X-ray densinometry, and micro-computed tomography. RESULTS. In vitro, this human angiogenic factors-enriched PRP resulted in better cellular proliferation and osteogenic differentiation. In vivo, increasing angiogenic potential of the PRP showed significantly higher blood perfusion around the defect and enhanced new bone formation around acellular bone graft material. CONCLUSION. Angiogenic factor-enriched PRP leads to faster and more extensive new bone formation in the critical size bone defect. The results implicate that rapid angiogenesis in the initial healing period by PRP could be supposed as a way to overcome short term effect of the rapid angiogenesis.