• Title, Summary, Keyword: mesh regeneration

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Two Dimensional Automatic Quadrilateral Mesh Generation for Metal Forming Analysis (소성 가공 공정 해석을 위한 2차원 사각 요소망 자동 생성)

  • Kim, Sang-Eun;Yang, Hyun-Ik
    • Korean Journal of Computational Design and Engineering
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    • v.14 no.3
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    • pp.197-206
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    • 2009
  • In a finite element analysis of the metal forming processes having large plastic deformation, largely distorted elements are unstable and hence they influence upon the result toward negative way so that adaptive remeshing is required to avoid a failure in the numerical computation. Therefore automatic mesh generation and regeneration is very important to avoid a numerical failure in a finite element analysis. In case of generating quadrilateral mesh, the automation is more difficult than that of triangular mesh because of its geometric complexity. However its demand is very high due to the precision of analysis. Thus, in this study, an automatic quadrilateral mesh generation and regeneration method using grid-based approach is developed. The developed method contains decision of grid size to generate initial mesh inside a two dimensional domain, classification of boundary angles and inner boundary nodes to improve element qualities in case of concave domains, and boundary projection to construct the final mesh.

Preliminary evaluation of a three-dimensional, customized, and preformed titanium mesh in peri-implant alveolar bone regeneration

  • Jung, Gyu-Un;Jeon, Jae-Yun;Hwang, Kyung-Gyun;Park, Chang-Joo
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.40 no.4
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    • pp.181-187
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    • 2014
  • Objectives: The purpose of this preliminary study is to evaluate the effectiveness of a customized, three-dimensional, preformed titanium mesh as a barrier membrane for peri-implant alveolar bone regeneration. Materials and Methods: Ten patients were recruited for this study. At the time of implant placement, all patients had fenestration or a dehiscence defect around the implant fixture. A mixture of particulate intraoral autologous bone and freeze-dried bone allograft was applied to the defect in a 1 : 1 volume ratio and covered by the preformed titanium mesh. A core biopsy specimen was taken from the regenerated bone four months postoperatively. Patients were followed for 12 months after the definitive prosthesis was placed. Results: Satisfactory bone regeneration with limited fibrous tissue was detected beneath the preformed titanium mesh. Histologic findings revealed that newly formed bones were well-incorporated into the allografts and connective tissue. New growth was composed of approximately 80% vital bone, 5% fibrous marrow tissue, and 15% remaining allograft. All implants were functional without any significant complications. Conclusion: The use of preformed titanium mesh may support bone regeneration by maintaining space for new bone growth through its macro-pores. This preliminary study presents the efficacy of a preformed titanium mesh as a ready-to-use barrier membrane around peri-implant alveolar bone defect. This preformed mesh is also convenient to apply and to remove.

Novel Mesh Regeneration Method Using the Structural Deformation Analysis for 3D Shape Optimization of Electromagnetic Device (전자소자의 3차원 형상최적화를 위한 구조변형 해석을 이용한 새로운 요소망 변형법)

  • Yao Yingying;Jae Seop Ryu;Chang Seop Koh;Dexin Xie
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.52 no.6
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    • pp.247-253
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    • 2003
  • A novel finite element mesh regeneration method is presented for 3D shape optimization of electromagnetic devices. The method has its theoretical basis in the structural deformation of an elastic body. When the shape of the electromagnetic devices changes during the optimization process, a proper 3D finite element mesh can be easily obtained using the method from the initial mesh. For real engineering problems, the method guarantees a smooth shape with proper mesh quality, and maintains the same mesh topology as the initial mesh. Application of the optimum design of an electromagnetic shielding plate shows the effectiveness of the presented method.

The effect of new bone formation of titanium mesh and demineralized freeze-dried bone (천공형 티타늄막과 탈회동결건조골의 신생골 형성에 대한 영향)

  • Lee, Yun-Ho;Park, Joon-Bong;Kwon, Young-Hyuk;Herr, Yeek;Kim, Chong-Kwan
    • Journal of Periodontal and Implant Science
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    • v.34 no.1
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    • pp.163-175
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    • 2004
  • This study was performed to evaluate bone formation in the calvaria of rabbit by the concept of guided bone regeneration with titanium mesh membrane and demineralized freeze-dried bone. The animal was sacrificed at 2 weeks, 4 weeks, 8 weeks, and 12 weeks after the surgery. Non-decalcified specimens were processed for histologic analysis. 1. The titanium mesh but the biocompatibility was excellent the cell-occlusiveness was feeble. 2. The cell-occlusiveness was feeble and also the soft tissue growth of the upper part of the newly-formed bone after operating was excellent in early stage. 3. The maintenance ability of the space for the GBR very was excellent. 4. The titanium mesh the tissue-integration was superior the wound fixation ability excellent. 5. The demineralized freeze-dried bone did not promote the bone regeneration. 6. With the lapse of time, formation quantity of the bone some it increased, it increased quantity very it was feeble. Within the above results, the titanium mesh for the guided bone regeneration was excellent, the dεmineralized freeze-dried bone confirmed does not promote bone regeneration.

3D printed cell-laden collagen and hybrid scaffolds for in vivo articular cartilage tissue regeneration

  • Koo, YoungWon;Choi, Eun-Ji;Lee, JaeYoon;Kim, Han-Jun;Kim, GeunHyung;Do, Sun Hee
    • Journal of Industrial and Engineering Chemistry
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    • v.66
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    • pp.343-355
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    • 2018
  • Current surgical treatments for osteochondral injuries include chondrocyte transplantation, osteochondral grafts, and bone marrow stimulation. Despite these approaches, repaired tissues often show limited regeneration resulting in fibrocartilage formation with poor mechanical properties. To overcome these shortcomings, a regenerative cell-laden scaffold therapy is a promising treatment option. In this study, we propose a three-dimensional (3D) micro-sized mesh structure using a cell-laden collagen bioink. To achieve the optimal cell-printing condition for the fabrication of cell-laden collagen structure, porous mesh collagen scaffold (PMCS) were assessed for the mechanical properties, printability and cell viability analysis. In vivo regenerative effects of PMCS were compared to the injecting hydrogel without pores (non-porous collagen scaffold (NPCS)), collagen/poly(${\varepsilon}$-caprolactone) (PCL) hybrid scaffold (CPHS)), and pure PCL scaffold (PPS). The porous mesh-structured/cell-laden collagen scaffold (PMCS) showed significantly enhanced cartilage regeneration in vivo compared to other conditions.

Guided Tissue Regeneration Using Barrier Membrane and Osseous Grafts in Surgically Created Furcation Defects in Dogs (성견의 외과적 치근이개부 골결손에 차폐막과 골이식재를 이용한 조직유도재생술시 치유양상)

  • Chung, Eun-Hee;Chung, Hyun-Ju
    • Journal of Periodontal and Implant Science
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    • v.26 no.4
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    • pp.967-987
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    • 1996
  • The present study was to evaluate the healing patterns of guided tissue regeneration( GTR) using resorbable $Vicryl^{(R)}$(polyglactin 910) mesh and nonresorbable expanded polytetrafluoroethylene(ePTFE) membrane with or without bone grafting using autogeneous bone and demineralized freeze-dried bone allograft(DFDBA) in the grade II furcation defects. Mucoperiosteal flaps were reflected buccally in the mandibular 2nd, 3rd and 4th premolar areas and furcation defects were created surgically by removing $5{\times}6mm$ alveolar bone in 4 dogs. Root surfaces were thoroughly debrided of periodontal ligament and cementum, and notches were placed on root surface at the most apical bone level. In the right and left mandibular quadrant, each tooth was received $Vicryl^{(R)}$ mesh(ACE Surgical Supply Co., USA) only, $Vicryl^{(R)}$ mesh with DFDBA, $Vicryl^{(R)}$ mesh with autogeneous bone grafts, ePTFE membrane($Core-tex^{(R)}$ membrane, W.L. Gore & Associates Inc., USA) only, ePTFE membrane with DFDBA or ePTFE membrane with autogeneous bone grafts. For the fluorescent microscopic examination, fluorescent agents were injected at 2, 4 and 8 weeks after surgery. Four weeks after surgery, 2 dogs were sacrificed and ePTFE membranes were removed from remaining 2 dogs, which were sacrificed at 12 weeks after surgery. Undecalcified tissues were embedded in methylmethacrylate and $10{\mu}m$ thick sections were cut in a buccolingual direction. These sections were stained with hematoxylin-eosin stain and Masson's trichrome stain, and evaluated by descriptive histology and linear measurements. The results were as follows : 1) $Vicryl^{(R)}$ mesh group showed less connective tissue attachment than ePTFE membrane group. 2) The combination of GTR using $Vicryl^{(R)}$ mesh and osseous grafts resulted in new attachment and new bone formation more than GTR using $Vicryl^{(R)}$ mesh only. 3) GTR using ePTFE membrane, with or without osseous grafts, enhanced periodontal regeneration. 4) Root resorption and dentoalveolar ankylosis were observed in the areas treated with the combination of GTR and DFDBA. It was suggested that the effect of adjunctive bone grafting in GTR procedure depends on the materials and the physical properties of barrier membranes. $Vicryl^{(R)}$ mesh performed a barrier function and the use of adjunctive bone grafting may enhance the periodontal regeneration.

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The effect of overlaying titanium mesh with collagen membrane for ridge preservation

  • Lim, Hyun-Chang;Lee, Jung-Seok;Choi, Seong-Ho;Jung, Ui-Won
    • Journal of Periodontal and Implant Science
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    • v.45 no.4
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    • pp.128-135
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    • 2015
  • Purpose: The aim of this study was to determine the effect of overlaying titanium mesh (TM) with an adjunctive collagen membrane (CM) for preserving the buccal bone when used in association with immediate implant placement in dogs. Methods: Immediate implant placements were performed in the mesial sockets of the third premolars of five dogs. At one site the TM was attached to the fixture with the aid of its own stabilizers and then covered by a CM (CM group), while the contralateral site received only TM (TM group). Biopsy specimens were retrieved for histologic and histomorphometric analyses after 16 weeks. Results: All samples exhibited pronounced buccal bone resorption, and a high rate of TM exposure was noted (in three and four cases of the five samples in each of the TM and CM groups, respectively). A dense fibrous tissue with little vascularity or cellularity had infiltrated through the pores of the TM irrespective of the presence of a CM. The distances between the fixture platform and the first bone-implant contact and the bone crest did not differ significantly between the TM and CM groups. Conclusions: Our study suggests that the additional use of a CM over TM does not offer added benefit for mucosal healing and buccal bone preservation.

3D Shape Optimization of Electromagnetic Device Using Design Sensitivity Analysis and Mesh Relocation Method (설계민감도해석과 요소망 변형법을 이용한 전자소자의 3차원 형상최적화)

  • ;Yao Yingying
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.52 no.7
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    • pp.307-314
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    • 2003
  • This paper presents a 3D shape optimization algorithm for electromagnetic devices using the design sensitivity analysis with finite element method. The structural deformation analysis based on the deformation theory of the elastic body under stress is used for mesh renewing. The design sensitivity and adjoint variable formulae are derived for the 3D finite element method with edge element. The results of sensitivity analysis are used as the input data of the structural analysis to calculate the relocation of the nodal points. This method makes it possible that the new mesh of analysis region can be obtained from the initial mesh without regeneration. The proposed algorithm is applied to the shape optimization of 3D electromagnet pole to net a uniform flux density at the target region.

Alveolar Bone Formation in Dogs using Vicryl Absorbable Mesh(Polyglactin 910) and Decalcified Freeze-Dried Bone Grafting (흡수성 차폐막과 동종탈회동결건조골 이식에 의한 치조골 재생의 병용효과)

  • Oh, Eun-Chung;Chung, Hyun-Ju;Kim, Young-Jun
    • Journal of Periodontal and Implant Science
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    • v.29 no.3
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    • pp.469-484
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    • 1999
  • The purpose of this study was to evaluate new bone formation following guided bone regeneration by resorbable and nonresorbable membrane. Six adult mongrel dogs were used. The first, second, third, fourth premolars in the mandible of each dog were extracted. Two months after tooth extraction, a buccal dehiscence defect was surgically created on each edentulous area. The experimental sites were divided into three groups according to the treatment modalities ; Group I-a: surgical treatment only ; Group I -b: allogenic decalcified freezed dried bone grafting ; Group II-a : e- PTFE membrane placement only ; Group II-b : allogenic decalcified freezed dried bone grafting and e-PTFE membrane placement ; Group III-a : Vicryl(R) mesh placement only ; Group III-b : allogenic decalcified freezed dried bone grafting and Vicryl(R) mesh placement . The animals were sacrificed at 8 weeks after operation and the specimens were prepared for histologic and histometric examination. The results were as follows : Clinically, all defect sites were healed without exposure of barrier membrane after the eight weeks. In Group I-a, dense connective tissues were impinged in the bony defect area. Well vascularized and fibrous bone marrow indicated that bone formation was still taking place was found. In Group I-b, in areas closer to the periphery, lamellation of the newly formed bone would found. In Group II-a, beneath the e-PTFE membrane a dense layer of connective tissue covering the most external portions of the regenerated tissue was seen. The new bone surfaces were lined with osteoid and osteoblast. In Group II-b, a dense layer of connective tissue covering the most external portions of the regenerated tissue was observed beneath the e-PTFE membrane. A notable amount of alveolar ridge regeneration was seen with new rigdes with well-contoured form. In Group III-a, the new bone surface were lined with osteoid and osteoblast, indicating active bone formation. A clear demarcation could not be noted between the host bone and new bone. In Group III-b, a notable amount of alveolar ridge regeneration was seen with new ridges assuming wellcontoured form. In areas closer to the periphery, lamellation of the newly formed bone would found. As histometric examination, the amount of bone formation was gained from $12.8mm^2$ to $26.3mm^2$. It was significantly greater in group II-b and group III-b compared to other groups(p<0.05) . These results suggest that Vicryl(R) mesh after DFDB grafting used in guided bone regeneration could create and sustain sufficient space for new bone formation.

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