• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.109-113
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• 2011

${\alpha},{\omega}$-Hydroxypropylpoly(dimethylsiloxane) was prepared from the reaction of a ${\alpha},{\omega}$-hydrogen polydimethylsiloxane with an allyl alcohol. MPE-g-poly(dimethylsiloxane) copolymer (MPES) was prepared from the graft copolymerization of MPE with ${\alpha},{\omega}$-hydroxypropyl group terminated PDMS. MPES/HDPE/EtO-CNT need to varify was prepared from the compounding of MPES, HDPE, and surface treated MWCNT with 4-ethoxybenzoic acid at $180^{\circ}C$. Melting point of the MPES/HDPE/EtO-CNT composite was decreased from 130 to $129^{\circ}C$ as increasing the content of MWCNT 10 to 20 wt% in the composite PTC characteristic of the MPES/HDPE/EtO-CNT composite was appeared at $120^{\circ}C$ as abruptly increasing the electrical resistivity at this temperature. The heighest PTC intensity of MPES/HDPE/EtO-CNT compsite at 10 wt% loading of EtO-CNT was 1.9.

• Polymer(Korea)
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• v.38 no.2
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• pp.156-163
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• 2014

Hydroxyapatite has osteoconductivity, biocompatibility and noninflammatory, and it has been used clinically as artificial bone. In this study, we prepared hydroxyapatite/poly(lactic-co-glycolic acid) (PLGA) scaffolds using 0, 10, 20, 40 and 60 wt% of hydroxyapatite. We analyzed compressive strength, SEM analysis and FTIR for mechanical property of 3D hydroxyapatite/PLGA scaffolds. For biocompatibility tests, cell proliferation and viability were measured via MTT assay and SEM. We analyzed RT-PCR, FACS, histology (H&E, ED-1) for anti-inflammatory effect. This study showed that hydroxyapatite hybrid scaffolds have low inflammatory reaction compared with the PLGA. This result has a potential for the application of artificial bone graft material.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.1
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• pp.1-11
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• 2012

Purpose: The purpose of this study was to evaluate the bone regeneration capacity of silk fibroin (SF) when combined with beta tricalcium phosphate (${\beta}$-tricalcium phosphate [TCP]) and rh-bone morphogenetic protein (BMP) in vivo by micro-computed tomography (CT), soft x-ray, and histological analysis. Methods: A total of 56 critical size defects formed by a trephine bur made on 28 adult female Spague-Dawley rats were used for this study and the defect size was 5.0 mm in diameter. The defects were transplanted with (1) no graft material (raw defect), (2) autogenous bone, (3) SF ($10{\mu}g$), (4) SF-BMP ($10{\mu}g$, $0.8{\mu}g$ each), and (5) SF+${\beta}$-TCP ($10{\mu}g$). At 4 and 8 weeks after operation, the experimental animals were sacrificed. Samples were evaluated with soft x-ray, histological examinations and 3-dimensional micro-CT analysis. Results: In the 3-dimensional micro-CT evaluation, bone volume and bone surface data were higher in the SF-BMP ($12.8{\pm}1.5$, $138.6{\pm}45.0$ each) (P<0.05) and SF-TCP ($12.3{\pm}1.5$, $144.9{\pm}30.9$ each) group than in the SF group ($6.1{\pm}3.3$, $77.2{\pm}37.3$ each) (P<0.05), except for the autogenous group ($15.0{\pm}3.0$, $190.7{\pm}41.4$ each) at 4 weeks. At 8 weeks, SF-BMP ($16.8{\pm}3.5$, $173.9{\pm}34.2$ each) still revealed higher (P<0.05) bone volum and surface, but SF-TCP ($11.3{\pm}1.5$, $1132.9{\pm}52.1$ each) (P=0.5, P=0.2) revealed the same or lower amount compared with the SF group ($13.8{\pm}2.7$, $127.5{\pm}44.8$ each). The % of bone area determined by radiodensity was higher in the SF-TCP ($31.4{\pm}9.1%$) and SF-BMP ($36.2{\pm}16.2%$) groups than in the SF ($19.0{\pm}10.4$) group at the period of 4 weeks. Also, in the histological evaluation, the SF-BMP group revealed lower inflammation reaction, lower foreign body reaction and higher bone healing than the SF group at postoperative 4 weeks and 8 weeks. The SF-TCP group revealed lower inflammation at 4 weeks, but accordingly, as the TCP membrane was absorbed, inflammatory and foreign body reaction are increased at 8 weeks. Conclusion: The current study provides evidence that the silk fibrin can be used as an effective grafted material for tissue engineering bone generation through a combination of growth factor or surface treatment.

• Journal of Chest Surgery
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• v.34 no.8
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• pp.591-596
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• 2001

Coronary artery bypass graft with cardiopulmonary bypass is a conventional method of operative revascularization of coronary artery disease. Because of many troubles of cardiopulmonary bypass such as systemic inflammatory reaction, mechanical trauma of blood components and coagulopathy, coronary artery bypass graft without cardiopulmonary bypass has been popularized. Material and Method: From March 1999 to September 2000, 35 patients under went CABG at our institution. Among them, 14 patients received CABG without the use of CPB and 21 patients under went CABG with the use of CPB. Mean operative time, mean postoperative tracheal intubation time, mean ICU stay, mean hospital stay, the amount of transfusion, postoperative use of inotropic agents, and postoperative changes of cardiac enzymes were compared in both groups. Result: There were differences between the CABG without CPB group and CABG with CPB group with regard to mean tracheal intubation time, the amount of transfusion and the elevation of postoperative cardiac enzymes(p<0.05). Conclusion: While CABG without CPB provided satisfactory results, more long term follow-up is required.

• Journal of Periodontal and Implant Science
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• v.29 no.3
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• pp.621-636
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• 1999

When mucoperiosteal flaps are positioned and sutured to desirable position, the wound contains several interface between tissues which differ fundamentally in composition & biological reaction. Thus the C-T surface of the flap will, on one hand, oppose another vascularized surface, and on the other, the avascular dental material for example, when root resoptions, fractured root, endodontic perforation, deep root carious lesions were filled with amalgam, glass ionomer, resin etc. Recently, a number of case report described the successful treatment of a subgingival root lesion with restorative material & free gingival graft, open flap surgery, but more objective research was needed . Most of study on restorative materials were concerned for cytotoxicity not for actual healing event on that materials and its influencing factors such as biocompatibility, surface wettability, surface topography . The aim of this in vitro study was to evaluate the effect of amalgam, resin modified glass ionomer, composite resin per se, and their surface roughness on the growth of human gingival fibroblast. The cells were obtained and placed on culture flask and incubated for 3 days with the prepared test materials. Then count the attached cell number with hemocytometer,(n=12) and 2 samples were examined with SEM about attachment cell morphology . Another 4 samples were evaluated on their surface roughness with Talysurf and average surface roughness value(Ra) were obtained. Statistical difference in attached cell number, roughness value were analyzed using ANOVA. The number of attached cell was as follows, for root dentin specimen 16.7${\pm}$4.41, resin modified glass ionomer 14.0${\pm}$4.15, resin 8.13${\pm}$3.63, amalgam 0.72${\pm}$3.33(${\times}10^3$). Between root dentin and resin-modified glass ionomer, no significant difference was observed, but resin, amalgam showed a significant less cell numbers than for root dentin, resin modified glass ionomer cement. SEM examination expressed many cell surface attachment apparatus in root dentin and resin modified glass ionomer specimens. For resin specimen, cell attachment was observed but exposed less appratus. The average surface roughness value are following results. Dentin specimen 0.6972${\pm}$ 0.104, resin modified glass ionomer 0.0822${\pm}$0.009, resin 0.0875${\pm}$0.005, amalgam 4.2145${\pm}$0.985(${\mu}m$). Between root dentin, resin-modified glass ionomer, and resin, no significant difference was observed, but amalgam showed a significant more rough surface than other groups. When evlauated the interrelationship between cell attachment and surface roughness, therefore, there was weak reverse correlation.(pearson correlation : - 0.593) These results suggest that resin modified glass ionomer have the favorable healing potential when used for subgingival restoration. And for relationship between cell attachment and surface characteristics, further investigations were needed.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.11 no.1
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• pp.117-129
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• 1989

The commercial availability of processed heterogenous bone has provided the surgeons with almost unlimited supply, avoidance of additional operation and prevention of the postoperative complications. In addition to these merits, unnecessary bone bank, easy availibility and storage have been achieved. The purpose of this study was to compare and examine the healing capacity of Kiel bone, Pyrost and Osteovit which used as the processed heterografts for the reconstruction of bony defect. Twenty rabbits weighing about 1.7-2.0 Kg were selected and divided into two groups. In experimental group A, the left mandibular defect was allowed to fill with blood, and the right defect was filled with Kiel bone. In experimental group B, the left defect was grafted with Pyrost, and the right with Osteovit. The experimental animals were sacrified after 1, 2, 4 and 8 weeks and the grafted site was studied histologically. To evaluate the strength of healed bone, 2 rabbits from each experimental group and a nonoperated control were sacrified at the 6th week after implantation and used for biometric testing on universal testing machine. The results obtained were as follows : 1. It was considered that these heterogenous bone grafts has feeble or absent immunogenicity since all of them appeared to evoke little inflammatory or forign body reaction. 2. In all experimental groups, new bone formation began from the adjacent region of host bone and extended progressively into the defect sites. New bone was partly formed within the intertrabecular space of the implant and gradually united with the bone that formed at the margin of the host bone. 3. With Pyrost bone formation was rapid and prominent comparing with other graft materials. 4. Osteovit was begun to be absorbed from 2 weeks, and Kiel bone from 4 weeks, however Pyrost was remained to be intact until the end of 8 weeks. 5. As the results of tensile test, the mean values of maximum tensile stress were 1.11${\uparrow}$ $Kgf/mm^{2}$ in Pyrost implanted specimens, 0.85 $Kgf/mm^{2}$ in Osteovit, 0.42 $Kgf/mm^{2}$ in Kiel bone, 0.66 $Kgf/mm^{2}$ in blood filled specimens and 1..13 $Kgf/mm^{2}$ in control. These results indicate that heterogenous bones grafted have little antigenicity to the host tissue, and that they mediate effectively osteoconduction by providing the scaffold for the bone formation. Pyrost and Osteovit appeared to be suitable for the clinical use.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.4
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• pp.306-312
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• 2010

Purpose: The purpose of this experiment was to evaluate the clinical effect of cultured autoglogous osteoblasts as a way to treat the defect of mandible in rabbits. Materials and Methods: Twelve rabbits were used to determine the rate of osteogenesis. The osteoblasts were obtained from the iliac crest of rabbits using aspiration. They were then cultured in Dulbecco's Modified Eagles's Medium (DMEM) with beta-glycerophosophatate, L-ascorbicacid, and dexamethasone to proliferate and differentiate osteoprogenitor cells. The expression of osteogenic markers were detected by reverse transcription-polymerase chain reaction (RT-PCR) and silver nitrate staining techniques. Five, 10-mm holes were placed in each rabbit mandible to simulate defective regions with the use of a low speed trephine bur. In the experimental group, the previously cited defects were grafted with both activated osteoblastic and autogenous bone. The control group, however, was only grafted with autogenous bone. Both groups were then analyzed at 2, 4, and 8-week intervals using bone histomorphometric analysis. Results: According to histomorphologic analysis, the rates of new bone formation at the 2, 4, and 8-week intervals were 36%, 51%, and 23% for the control group, respectively; 52%, 39%, and 28%, for the experimental group, respectively. The experimental group showed higher rates of new bone formation compared to the control group at both the 2-week and 8-week interval. Conclusion: Bone marrow-derived osteoblasts seems to be a promising bone graft material.

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.75-82
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• 1996

Acrylic acid was graft-copolymerized on polyethylene film in the presence of additives such as acid and $FeSO_4(NH_4)_2SO_4{\cdot}6H_2O$ using peroxide grafting technique by ${\gamma}$-ray and electron beam, and the effect of $FeSO_4(NH_4)_2SO_4{\cdot}6H_2O$ and acid on the grafting yield was evaluated. The grafting mechanism and the physical property of grafted films were also examined. The results showed that the inclusion of $FeSO_4(NH_4)_2SO_4{\cdot}6H_2O$ in acidified acrylic acid grafting solution was extremely beneficial and led to a most unusual enhancement effect in the radiation grafting. In the other hand, inclusion of mineral acid in the grafting solution in the absence of $FeSO_4(NH_4)_2SO_4{\cdot}6H_2O$ could not lead to he suitable grafting reaction by the severe homopolymerization of acrylic acid. The addition of $H_2SO_4$, and HCl led to much higher grafting yield than $HNO_3$and $CH_3COOH$. It was shown that grafting yield of ${\gamma}$-ray irradiated-polyethylene was higher than that of electron beam irradiated polyethylene.

• KSBB Journal
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• v.21 no.6 s.101
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• pp.439-443
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• 2006

Biocompatibility and tissue regenerating capacity are essential characteristics in the design of collagenous biomaterials for tissue engineering. Attachment of glycosaminoglycans to collagen may add to these characteristics by creating an appropriate micro-environment. In this study, porous type I collagen matrices were crosslinked using dehydrothermal treatment and 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide, in the presence and absence of chondroitin sulfate (CS). The scaffold like discs in 3 mm diameter were inserted into the intralamellar stromal pockets of rabbit cornea. In 8 weeks of follow up, clinical evaluation including corneal neovascularization, opacity and transparency of the graft scaffold was performed, and the inflammatory reaction and migration of corneal fibroblast were evaluated histologically. No inflammation, neovascularization and opacity in any of the implant were observed. CS increased the corneal fibroblast invasion and the transparency. It is concluded that the type I collagen sponge showed a biocompatibility in corneal stromal layer and addition of CS slightly improved the quality of the bioartificial corneal stromal layer. These results could be useful for the development of corneal substitutes.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.6
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• pp.459-466
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• 2011

Purpose: This study evaluated the capability of bone formation with silk fibroin/nano-hydroxyapatite/corn starch composite scaffold as a bone defect replacement matrix when grafted in a calvarial bone defect of rabbits $in$ $vivo$. 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 10% nano-hydroxyapatite/30% corn starch/60% composite scaffold was grafted into the right parietal bone (experimental group). The left side (control group) was grafted with a nano-hydroxyapatite (30%)/corn starch (70%) scaffold. 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 with Masson's trichrome for histological and histomorphometric analysis. Results: The average ${\mu}CT$ and histomorphometric measures of bone formation were higher in the control group than in the experimental group at 4 weeks and 8 weeks after surgery though not statistically significant ($P$ >0.05). Conclusion: The rabbit calvarial defect was not successfully repaired by silk fibroin/nano-hydroxyapatite/corn starch composite scaffold and may have been due to an inflammatory reaction caused by silk powder. In the future, the development of composite bone graft material based on various components should be performed with caution.