• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.1
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• pp.9-15
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• 2010

Aim of the study: As an injectable scaffold, MPEG-PCL diblock copolymer was applied in bone tissue engineering. In vivo bone formation was evaluated by soft X-ray, histology based on the rat calvarial critical size defect model. Materials and Methods: New bone formation was evaluated with MPEG-PCL diblock copolymer in rat calvarial critical size bone defect. No graft was served as control. 4, 8 weeks after implantation, gross evidence of bone regeneration was evaluated by histology and soft X-ray analysis. Results: The improved and effective bone regeneration was achieved with the BMP-2 and osteoblasts loaded MPEG-PCL diblock copolymer. Conclusion: It was confirmed that MPEG-PCL temperature sensitive hydrogels was useful as an injectable scaffold in bone regeneration.

• Macromolecular Research
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• v.16 no.8
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• pp.704-710
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• 2008

Injectable hydrogels are quite promising materials due to their potential to minimize invasive implantation and this provides versatile fitness irrespective of the damaged regions and facilitates the incorporation of bioactive agents or cells. In situ gel formation through stereocomplex formation is a promising candidate for injectable hydrogels. In this paper, a new series of enantiomeric, four-arm, PEG-PLA block copolymers and their stereocomplexed hydrogels were prepared by bulk ring-opening polymerization of D-lactide and L-lactide, respectively, with stannous octoate as a catalyst. The prepared polymers were characterized by $^1H$ nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FT IR) spectroscopy, gel permeation chromatography (GPC) and thermal gravitational analysis (TGA), confirming the tailored structure and chain lengths. The swelling and degradation behavior of the hydrogels formed from a selected copolymer series were observed in different concentrations. The degradation rate decreased with increasing polymer content in the solution. The rheological behavior indicated that the prepared hydrogel underwent in situ gelation and had favorable mechanical strength. In addition, its feasibility as an injectable scaffold was evaluated using a media dependence test for cell culture. A Tris solution was more favorable for in situ gel formation than PBS and DMEM solutions were. These results demonstrated the in situ formation of hydrogel through the construction of a stereocomplex with enantiomeric, 4-arm, PEG-PLA copolymers. Overall, enantiomeric, 4-arm, PEG-PLA copolymers are a new species of stereocomplexed hydrogels that are suitable for further research into injectable hydrogels.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.252-252
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• 2006

Utilizing the existence of the induction period in photo-polymerization, we propose a new injection method of photo-polymerizable, thermocrosslinking hydrogels made of di-acrylated Pluronic F127 (DA-PF127). This method can solve the problem of fast dissolution of thermal gelation as a scaffold and the disadvantages of the existing injection method that photo-polymerize di-acrylated Pluronic polymer after injection using optical fiber. Injectable gelation of DA-PF127 by the proposed method was demonstrated both in vitro and in vivo. The enhanced stability by this novel photo-polymerization strategy was confirmed by the more sustained release of loaded protein as well as the prolonged degradation time of the hydrogels.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.3
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• pp.146-152
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• 2009

Traditional surgical method or injection using filler is performed for soft tissue augmentation. Surgical methods have disadvantage of surgical morbidity. Commercially available injectable materials have the disadvantages such as resorption, short-term effect. repeated application and hypersensitivity. Significant shortcoming of cell therapy using autologous fibroblasts is delay of treatment effect. Chitosan/${\beta}$-glycerol phosphate (GP) solution has thermosensitive property and allows sol-gel transition at physiologic pH and temperature. These properties may resolve the delay of treatment effect. The purposes of this study are to evaluate the viscosity and pH changes of chitosan/${\beta}$-GP solutions and to evaluate the effect of chitosan/${\beta}$-GP solution on fibroblast proliferation and production of collagen. We measured the viscosity and pH as function of temperature, of the solution containing 1:0.7, 1:0.75, 1:0.8 chitosan (1, 10, 100, 700 kDa) /${\beta}$-GP. Fibroblasts from ears of 5 rats were cultured in chitosan/${\beta}$-GP solutions for 3 weeks. Cell proliferation and collagen contents were measured every week with WST (water-soluble tetrazolium salt) assay and Collagen assay respectively. The Results are 1) Chitosan(100 kDa<)/${\beta}$-GP solution (1:0.75) showed sol-gel transition at physiologic pH and body temperature and injectable properties. It will enable to resolve the delay in treatment effect 2) Cell proliferation and total collagen contents of the control group were increased with time. However, these decreased after the 1st week in experimental group 3) Collagen contents in the experimental group are higher than that of control group. Chitosan/${\beta}$-GP solution may provide favorable conditions for cell function

• Restorative Dentistry and Endodontics
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• v.41 no.2
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• pp.98-105
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• 2016

Objectives: The biocompatibility of two experimental scaffolds for potential use in revascularization or pulp regeneration was evaluated. Materials and Methods: One resilient lyophilized collagen scaffold (COLL), releasing metronidazole and clindamycin, was compared to an experimental injectable poly(lactic-co-glycolic) acid scaffold (PLGA), releasing clindamycin. Human dental pulp stem cells (hDPSCs) were seeded at densities of $1.0{\times}10^4$, $2.5{\times}10^4$, and $5.0{\times}10^4$. The cells were investigated by light microscopy (cell morphology), MTT assay (cell proliferation) and a cytokine (IL-8) ELISA test (biocompatibility). Results: Under microscope, the morphology of cells coincubated for 7 days with the scaffolds appeared healthy with COLL. Cells in contact with PLGA showed signs of degeneration and apoptosis. MTT assay showed that at $5.0{\times}10^4$ hDPSCs, COLL demonstrated significantly higher cell proliferation rates than cells in media only (control, p < 0.01) or cells co-incubated with PLGA (p < 0.01). In ELISA test, no significant differences were observed between cells with media only and COLL at 1, 3, and 6 days. Cells incubated with PLGA expressed significantly higher IL-8 than the control at all time points (p < 0.01) and compared to COLL after 1 and 3 days (p < 0.01). Conclusions: The COLL showed superior biocompatibility and thus may be suitable for endodontic regeneration purposes.

• Proceedings of the KAIS Fall Conference
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• 2011.12a
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• pp.330-333
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• 2011

Allomatrix (Wright Medical Tech, Inc., USA), is a newly designed, injectable putty with a reliable demineralized bone matrix(DBM), derived from human bone. The compound contains 86% DBM and other bone growth factors such as bone morphogenic protein (BMP)-2, BMP-4, insulin-like growth factor (IGF)-1, and transforming growth factor (TGF)-${\beta}1$. It has excellent os-teoinduction abilities. In addition, DBM is known to have osteoconduction capacity as a scaffold due to its collagen matrix. This product contains a powder, which is a mix of DBM and surgical grade calcium sulfate as a carrier. A practitioner can blend the powder with calcium sulfate solution, making a putty-type material which has the advantages of ease of handling, better fixation, and no need for a membrane, because it can function as membrane itself. This study reports the clinical and radiographic results of various guided bone regeneration cases using Allomatrix, demonstrating its strong potential as a graft material.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.5
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• pp.420-424
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• 2011

Allomatrix (Wright Medical Tech, Inc., Arlington, Tenn, USA), is a newly designed, injectable putty with a reliable demineralized bone matrix (DBM), derived from human bone. The compound contains 86% DBM and other bone growth factors such as bone morphogenic protein (BMP)-2, BMP-4, insulin-like growth factor (IGF)-1, and transforming growth factor (TGF)-${\beta}1$. It has excellent osteoinduction abilities. In addition, DBM is known to have osteoconduction capacity as a scaffold due to its collagen matrix. This product contains a powder, which is a mix of DBM and surgical grade calcium sulfate as a carrier. A practitioner can blend the powder with calcium sulfate solution, making a putty-type material which has the advantages of ease of handling, better fixation, and no need for a membrane, because it can function as membrane itself. This study reports the clinical and radiographic results of various guided bone regeneration cases using Allomatrix, demonstrating its strong potential as a graft material.

• Archives of Plastic Surgery
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• v.45 no.6
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• pp.564-571
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• 2018

Background Chronic wounds occur due to failure of the normal healing process, associated with a lack of deposition of cellular components and a suitable microenvironment such as the extracellular matrix (ECM). Acellular dermal matrix (ADM) is viewed as an ECM substitute, and a paste-type ADM has recently been introduced. We hypothesized that CGPaste, an injectable paste-type ADM, could serve as a scaffold and promote wound healing. Methods We retrospectively studied seven patients in whom CGPaste was applied between 2017 and 2018, who had pressure ulcers, necrotizing fasciitis, diabetic foot ulcers, traumatic defects, and osteomyelitis. The goal of applying CGPaste was to achieve complete wound healing with re-epithelialization or growth of granulation tissue, depending upon the wound bed status. CGPaste was injected based on the wound size along with the application of a dressing. Results Four of the seven patients showed granulation tissue on their wound bed, while the other three patients had a bony wound bed. The mean wound area was $453.57mm^2$ and the depth was 10.71 mm. Wound healing occurred in five of the seven patients (71.43%). The mean duration of complete healing was 2.4 weeks. Two patients showed failure due to paste absorption (29.57%); these patients had wound beds comprising bone with relatively large and deep wounds ($40{\times}30$ and $30{\times}20mm^2$ in area and 15 and 10 mm in depth). Conclusions CGPaste is an effective option for coverage of small and deep chronic wounds for which a flap operation or skin grafting is unfeasible.