• Restorative Dentistry and Endodontics
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• v.35 no.4
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• pp.238-245
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• 2010

Numerous cases about additional growth of roots or pulp tissue regeneration by using various intracanal medicaments in immature permanent teeth with periapical or pulpal disease have been reported. The underlying mechanism has not been clearly delineated, but it has been widely accepted that undifferentiated mesenchymal cells and stem cells are involved. Moreover, the growth and deposition of osteoid or cementoid tissues have been observed in regenerated pulp and roots. This new and non-invasive treatment has brightened the future of endodontics, and enlarged the vision of regenerative root canal treatment with multi-potent stem cells and various tissue engineering techniques.

• Implantology
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• v.18 no.2
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• pp.120-138
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• 2014

Purpose: The purpose of this study was to review the outcomes of a series of studies on tissue regeneration conducted in multiple institutions including the Department of Periodontology, College of Dentistry, Yonsei University. Materials and Methods: Studies were performed divided into the following three subjects; 1) Development of three-dimensional nano-hydroxyapatite (n-HA) scaffold for facilitating drug release and cell adhesion. 2) Synergistic effects of bone marrow-derived mesenchymal stem cells (BMMSC) application simultaneously with platelet-rich plasma (PRP) on HA scaffolds. 3) The efficacy of silk scaffolds coated with n-HA. Also, all results were analyzed by subjects. Results: Hollow hydroxyapatite spherical granules were found to be a useful tool for the drug release and avidin-biotin binding system for cell attachment. Also, BMMSC simultaneously with PRP applied in an animal bone defect model was seen to be more synergistic than in the control group. But, the efficacy of periodontal ligament cells and dental pulp cells with silk scaffolds could not be confirmed in the initial phase of bone healing. Conclusion: The ideal combination of three elements of tissue engineering-scaffolds, cells and signaling molecules could be substantiated due to further investigations with the potentials and limitations of the suggested list of studies.

• Animal cells and systems
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• v.5 no.2
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• pp.91-99
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• 2001

Vertebrates regenerate tissues in three ways: proliferation of cells that maintain some or all of their differentiated structure and function, redifferentiation of mature cells followed by proliferation and redifferentiation into the same cell type or transdetermination to another cell type, and activation of restricted lineage stem cells, which have the ability to transdetermine to different lineages under the appropriate conditions. The behavior of the cells during regeneration is regulated by growth factors and extracellular matrix molecules. Some non-regenerating tissues are now known to harbor stem cells which, though they form scar tissue in vivo, are capable of producing new tissue-specific cells in vitro, suggesting that the injury environment inhibits latent regenerative capacity. Regenerative medicine seeks to restore tissues via transplantation of stem cell derivatives, implantation of bioartificial tissues, or stimulation of regeneration in vivo. These approaches have been partly successful, but several research issues must be addressed before regenerative medicine becomes a clinical reality.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.3
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• pp.104-109
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• 2023

Electrospinning was performed using an eco-friendly solvent composed of acetic acid, ethyl acetate and distilled water to investigate the effect of gelatin concentration on mechanical properties and cytotoxicity of absorbable poly(D,L-lactic acid) (PDLLA)/gelatin blend membrane. The tensile stress, strain at break, and WUC of the PDLLA/gelatin (97/3) scaffold at 26 wt% concentration were determined to be 3.9 ± 0.7 MPa, 37 ± 1.3 %, and 273 ± 33 %, respectively. FT-IR results revealed that PDLLA and gelatin were bound only by van der Waals interactions. The cell viability of PDLLA/gelatin membranes containing 0 %, 1 %, 2 %, 3 %, and 4 % gelatin were more than 100 %, which makes all membranes highly suitable as a barrier membrane for absorbable periodontal tissue regeneration due to their marketed physical properties and biocompatibility.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.2
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• pp.220-229
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• 2008

Purpose: The present study was aimed to examine the effect of acellular dermal matrix ($AlloDerm^{(R)}$) grafted to the experimental tissue defect on tissue regeneration. Materials and Methods: Male albino rabbits were used. Soft tissue defects were prepared in the external abdominal oblique muscle. The animals were then divided into 3 groups by the graft material used: no graft, autogenous dermis graft, and $AlloDerm^{(R)}$ graft. The healing sites were histologically examined at weeks 4 and 8 after the graft. In another series, critical sized defects with 8-mm diameter were prepared in the right and left iliac bones. The animals were then divided into 5 groups: no graft, grafted with autogenous iliac bone, $AlloDerm^{(R)}$ graft, $AlloDerm^{(R)}$ graft impregnated with rhBMP-2, and $AlloDerm^{(R)}$ graft with rhTGF-${\beta}1$. The healing sites of bone defect were investigated with radiologic densitometry and histological evaluation at weeks 4 and 8 after the graft. Results: In the soft tissue defect, normal healing was seen in the group of no graft. Inflammatory cells and foreign body reactions were observed in the group of autogenous dermis graft, and the migration of fibroblasts and the formation of vessels into the collagen fibers were observed in the group of $AlloDerm^{(R)}$ graft. In the bone defect, the site of bone defect was healed by fibrous tissues in the group of no graft. The marked radiopacity and good regeneration were seen in the group of autogenous bone graft. There remained the traces of $AlloDerm^{(R)}$ with no satisfactory results in the group of $AlloDerm^{(R)}$ graft. In the groups of the $AlloDerm^{(R)}$ graft with rhBMP-2 or rhTGF-${\beta}1$, there were numerous osteoblasts in the boundary of the adjacent bone which was closely approximated to the $AlloDerm^{(R)}$ with regeneration features. However, the fibrous capsule also remained as in the group of $AlloDerm^{(R)}$ graft, which separated the $AlloDerm^{(R)}$ and the adjacent bone. Conclusions: These results suggest that $AlloDerm^{(R)}$ can be useful to substitute the autogenous dermis in the soft tissue defect. However, it may not be useful as a bone graft material or a carrier, since the bone defect was not completely healed by the bony tissue, regardless of the presence of osteogenic factors like rhBMP-2 or rhTGF-${\beta}1$.

• Plant Resources
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• v.2 no.1
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• pp.10-15
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• 1999

In vitro shoot regeneration from cotyledon and hypocotyl explants derived from germinating mature Impatiens seeds. The induction of organogenetic tissue was also influenced by the cotyledon and hypocotyl. Multiple shoot induction was higher in hypocotyl than in the cotyledon explant with Thidiazuron and a NAA medium.

• Journal of Periodontal and Implant Science
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• v.29 no.3
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• pp.553-560
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• 1999

The aim of the present study was to evaluate the effect of the expanded polytetrafluoroethylene (e-PTFE) membrane exposure on the initial healing of the periodontal tissue in guided tissue regeneration (GTR) procedure. 90 sites selected from 90 patients were treated with gingival flap surgery supported by an e-PTFE membrane. The material included angular bony defects with probing attachment loss of > 5mm or degree II furcation involvement. Treated sites were classified with membrane exposure group and non-exposure group at membrane removal and evaluated healing type. The results were obtained as follows. 1. e-PTFE membrane was exposed at 61 sites (67.8%) among 90 sites. 2. Thirteen sites (14.4%) depicted rapid healing type, 65 sites (72.2%) depicted typical healing type, 9 sites (10%) showed delayed healing type and 3 sites (3.3%) were categorized as adversed healing type. 3. In e-PTFE membrane exposure group, 1 site (1.6%), 51 sites (83.6%), 6 sites (9.8%) and 3 sites (4.9%) showed rapid healing type, typical healing type, delayed healing type and adverse healing type respectively. 4. In e-PTFE membrane non-exposure group, 12 sites (41.3%), 14 sites (48.3%) and 3 sites (10.3%) showed rapid healing type, typical healing type and delayed healing type respectively. Adverse healing type was not observed. 5. The rate of favourable healing between e-PTFE membrane exposure group and non-exposure group was not statistically significant(p=0.56). These results suggest that the prevention of membrane exposure may be important to obtain rapid healing type. However favourable healing could be obtained with stringent infection control program even if membrane was exposed.

• Journal of Periodontal and Implant Science
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• v.47 no.6
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• pp.363-371
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• 2017

Purpose: The purpose of this study was to investigate the feasibility of regenerative therapy with a collagenated bone graft and resorbable membrane in intrabony defects, and to evaluate the effects of the novel extracellular matrix (ECM)-based membrane clinically and radiologically. Methods: Periodontal tissue regeneration procedure was performed using an ECM-based resorbable membrane in combination with a collagenated bovine bone graft in intrabony defects around the teeth and implants. A novel extracellular matrix membrane (NEM) and a widely-used membrane (WEM) were randomly applied to the test group and the control group, respectively. Cone-beam computed tomography images were obtained on the day of surgery and 6 months after the procedure. Alginate impressions were taken and plaster models were made 1 week and 6 months postoperatively. Results: The quantity of bone tissue, the dimensional changes of the surgically treated intrabony defects, and the changes in width and height below the grafted bone substitutes showed no significant difference between the test and control groups at the 6-month examination. Conclusions: The use of NEM for periodontal regeneration with a collagenated bovine bone graft showed similar clinical and radiologic results to those obtained using WEM.

• Restorative Dentistry and Endodontics
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• v.44 no.2
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• pp.20.1-20.8
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• 2019

Objectives: To achieve pulp-dentin complex regeneration with tissue engineering, treatment efficacies and safeties should be evaluated using in vivo orthotopic transplantation in a sufficient number of animals. Mice have been a species of choice in which to study stem cell biology in mammals. However, most pulp-dentin complex regeneration studies have used large animals because the mouse tooth is too small. The purpose of this study was to demonstrate the utility of the mouse tooth as a transplantation model for pulp-dentin complex regeneration research. Materials and Methods: Experiments were performed using 7-week-old male Institute of Cancer Research (ICR) mice; a total of 35 mice had their pulp exposed, and 5 mice each were sacrificed at 1, 2, 4, 7, 9, 12 and 14 days after pulp exposure. After decalcification in 5% ethylenediaminetetraacetic acid, the samples were embedded and cut with a microtome and then stained with hematoxylin and eosin. Slides were observed under a high-magnification light microscope. Results: Until 1 week postoperatively, the tissue below the pulp chamber orifice appeared normal. The remaining coronal portion of the pulp tissue was inflammatory and necrotic. After 1 week postoperatively, inflammation and necrosis were apparent in the root canals inferior to the orifices. The specimens obtained after experimental day 14 showed necrosis of all tissue in the root canals. Conclusions: This study could provide opportunities for researchers performing in vivo orthotopic transplantation experiments with mice.

• International Journal of Stem Cells
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• v.16 no.1
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• pp.93-107
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• 2023

Background and Objectives: Chronic periodontitis can lead to alveolar bone resorption and eventually tooth loss. Stem cells from exfoliated deciduous teeth (SHED) are appropriate bone regeneration seed cells. To track the survival, migration, and differentiation of the transplanted SHED, we used super paramagnetic iron oxide particles (SPIO) Molday ION Rhodamine-B (MIRB) to label and monitor the transplanted cells while repairing periodontal bone defects. Methods and Results: We determined an appropriate dose of MIRB for labeling SHED by examining the growth and osteogenic differentiation of labeled SHED. Finally, SHED was labeled with 25 ㎍ Fe/ml MIRB before being transplanted into rats. Magnetic resonance imaging was used to track SHED survival and migration in vivo due to a low-intensity signal artifact caused by MIRB. HE and immunohistochemical analyses revealed that both MIRB-labeled and unlabeled SHED could promote periodontal bone regeneration. The colocalization of hNUC and MIRB demonstrated that SHED transplanted into rats could survive in vivo. Furthermore, some MIRB-positive cells expressed the osteoblast and osteocyte markers OCN and DMP1, respectively. Enzyme-linked immunosorbent assay revealed that SHED could secrete protein factors, such as IGF-1, OCN, ALP, IL-4, VEGF, and bFGF, which promote bone regeneration. Immunofluorescence staining revealed that the transplanted SHED was surrounded by a large number of host-derived Runx2- and Col II-positive cells that played important roles in the bone healing process. Conclusions: SHED could promote periodontal bone regeneration in rats, and the survival of SHED could be tracked in vivo by labeling them with MIRB. SHED are likely to promote bone healing through both direct differentiation and paracrine mechanisms.