• The Journal of Korean Institute of Communications and Information Sciences
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• v.6 no.1
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• pp.45-50
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• 1981

Infrasonic transducer made with dielectric materials, such as polytetrafluoroethyleme(PTFE)film. The experimental result obtained that the response is within $\pm$1.5dB from 0.1Hz to 7KHz, and that sensitivities of typical transducer are fixed -60dB. The time constant of the transducer at room temperature is over 60 years, and the activation energy of the value of 1.1eV at 343K acquired. This transducer can have application to high-quality communication system, seismological observation etc.

• 대한치주과학회:학술대회논문집
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• 2004.11a
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• pp.71-71
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• 2004

• 대한치주과학회:학술대회논문집
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• 2009.05a
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• pp.48-48
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• 2009

• Journal of Periodontal and Implant Science
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• v.35 no.1
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• pp.251-261
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• 2005

Alveolar ridge defects may limit or restrict placement of implants. The purpose of this study was to evaluate clinical and histopathologic results which occur following guided bone regeneration using platelet-rich plasma, bovine bone powder and e-PTFE membrane in the localized alveolar bone defects. Ten patients who required guided bone regeneration in implant placemnet, were slelected. Alveolar crest height and width were measured at baseline and, afer 2nd surgery 5 months later At 5 months , we obtained histopathological results as follows: 1. Alveolar crest height was an average of $8.20{\pm}3.74$ mm preoperatively and decreased to an average of $7.40{\pm}1.84$ mm postoperatively. There was no significant difference. 2. Alveolar crest width was an average of $4.25{\pm}2.03$ mm preoperatively and significantly increased to an average of $7.20{\pm}2.44$ mm postoperatively (P<0.01) 3. The change of Alveolar crest height and width were $0.80{\pm}1.40$ mm, $2.95{\pm}1.09$ mm 4. Histopathological evaluations revealed new bone formation with graft material and laminated bone containing the presence of osteocyte-like cell In conclusion, guided bone regeneration using platelet-rich plasma, bovine bone powder and e-PTFE membrane would provide a viable therapeutic alternative for implant placement in the localized alveolar defect or implant failure

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.80-88
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• 1996

The aim of the present investigation was to see the effect of combined use of PDGF BB and IGF -1 on the guided tissue regeneration(GTR) using barrier membrane in the treatment of human furcation involvement. Twelve patients with initially diagnosed as having moderate to advanced adult periodontitis with mandibular class II buccal furcation defects have been wer selected. Initial scaling and root planing has been performed and baseline data consisting of probing depths and attachment levels have been recorded prior to surgical procedures. The GTR procedures using either barrier membrane(control : ePTFE) alone or together with the application of PDGF - BB and IGF -l(experimental : ePTFE+PDGF/IGF) have been done under the routine guidelines. During the surgery, the distance from CEJ either to the bottom of the bone defects(CEJ - BD) or to the bone crest(CEJ-BC) were measured. Horizontal distance to the deepest area in the furcal defects were measured from the reference line connection the most prominent bony walls of the two buccal roots. 6 months following the GTR therapy, all the measurements were made repeatedly. The probing attachment gain of the experimental and the control grous were 2.14mm and l.07mm, respectively with no statically significnant difference. Amont of vertical bone fill in the experimental and the control groups were 2.43mm and 2.29mm, rexpectively. Amonut of horizontal bone fill were 2.86mm in the experimental group and 2.17mm in the control group, respectively. However, there were no significant differences in the amount of bone fill(both vertical and horizontal)between the two groups.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.113-127
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• 2002

The purpose of this study is to evaluate histologically the tissue response and resorption of various nonresorbable and resorbable suture materials used for periodontal surgery, using a subcutaneous model on the dorsal surface of the rat. In this study, 10 Sprague-Dawley male rats (mean BW 150gm) were used and the commercially available materials included polyglactin 910, pain gut, nylon, e-PTFE. Animals were sacrificed at 3 days, 1, 2 and 4 weeks after implantation of various nonresorbable and resorbable suture materials. Specimens were prepared with Hematoxylin-Eosin stain for light microscopic evaluation. The results of this study were as follows: 1. Resorption : The resorption of plain gut was showed at 1 week after implantation, was lost their structure and almost resorbed at 4 weeks. The resorption of polyglactin 910 was started at 2 weeks and slowly absorbed untill 4 weeks. 2. Tissue response : Plain gut showed persistent and severe inflammatory reactions from 3 days to 4 weeks. Polyglactin 910, e-PTFE and nylon showed mild inflammatory reactions. Suture material should be biocompatible and be able to be functioned until tissue tensile strength reaches maximum level. In this study, polyglactin 910, nylon and e-PTFE are considered to be proper suture materials for periodontal surgery.

• Journal of Chest Surgery
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• v.54 no.2
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• pp.81-87
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• 2021

Background: Artificial grafts such as polyethylene terephthalate (Dacron) and expanded polytetrafluoroethylene (ePTFE) are used for various cardiovascular surgical procedures. The compliance properties of prosthetic grafts could affect hemodynamic energy, which can be measured using the energy-equivalent pressure (EEP) and surplus hemodynamic energy (SHE). We investigated changes in the hemodynamic energy of prosthetic grafts. Methods: In a simulation test, the changes in EEP for these grafts were estimated using COMSOL MULTIPHYSICS. The Young modulus, Poisson ratio, and density were used to analyze the grafts' material properties, and pre- and post-graft EEP values were obtained by computing the product of the pressure and velocity. In an in vivo study, Dacron and ePTFE grafts were anastomosed in an end-to-side fashion on the descending thoracic aorta of swine. The pulsatile pump flow was fixed at 2 L/min. Real-time flow and pressure were measured at the distal part of each graft, while clamping the other graft and the descending thoracic aorta. EEP and SHE were calculated and compared. Results: In the simulation test, the mean arterial pressure decreased by 39% for all simulations. EEP decreased by 42% for both grafts, and by around 55% for the native blood vessels after grafting. The in vivo test showed no significant difference between both grafts in terms of EEP and SHE. Conclusion: The post-graft hemodynamic energy was not different between the Dacron and ePTFE grafts. Artificial grafts are less compliant than native blood vessels; however, they can deliver pulsatile blood flow and hemodynamic energy without any significant energy loss.

• 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.

• Journal of Periodontal and Implant Science
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• v.37 no.4
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• pp.791-803
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• 2007

The purpose of this study was to evaluate exophytically vertical bone formation in residual ridge of the beagle dog by the concept of guided bone regeneration with a titanium reinforced e-PTFE membrane combined with irradiated cancellous human bone. Twelve male beagle dogs(mean age 1.5 years and mean weight 12kg) were used for this study. The alveolar ridges after extraction of all mandibular premolars were surgically and horizontally removed. At 8 weeks after extractions, full-thickness flap was reflected and cortical bone was removed with round bur and copious irrigation. Rectangular parallelepiped(10mm in length, 5mm in width, and 4mm in height) bended with titanium-reinforced e-PTFE(TR e-PTFE) membrane was placed on the decorticated alveolar ridge, fixed with metal pins and covered with full-thickness flap and assigned as a control group. Test groups ere treated with TR e-PTFE membrane filled with irradiated cancellous human bone. Of twelve beagle dogs, four control dogs and four test dogs without membrane exposure to oral cavity were sacrificed at 8 and 16 weeks respectively. The surgical sites were dissected out, fixed in 4% buffered formaldehyde, dyed using a Villanueva staining technique, and processed for embedding in plastic resin. The cutting and grinding methods were routinely processed for histologic and histomophometric analyis of exophytic bone formation as well as statistical analysis. The results of this study were as follows: 1. Exophytic bone formation in the both of experimental groups was increased respectively after surgery from 23.40% at 8 weeks to 46.26% at 16 weeks in the control groups, from 40.23% at 8 weeks to 47.11% at 16 weeks in the test groups(p<0.05). 2. At 8 weeks after surgery, exophytic bone formation was made 40.23% in the test groups and 33.40% in the control groups. Exophytic bone formation was significantly made in the test group more than in the control group. At 16 weeks after surgery, exophytic bone formation was made 44.11% in the test groups and 46.26% in the control groups. Exophytic bone formation was made in the test groups more than in the control groups, but there was no statistically significant differences. 3. The membrane was fixed with metal pins to closely contact it to the bone surface. So, collapse and deviation of the membrane could be prevented and in growth of connective tissue also could be blocked from the periphery of the membrane. On the basis of these findings, wee suggest that intraoral experimental model for exophytic bone formation may be effective to evaluate the effect of bone graft material. And it indicates that combined use of membrane and ICB graft material is more effective than use of membrane only for exophytic bone formation.

• Journal of Chest Surgery
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• v.30 no.5
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• pp.533-536
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• 1997

We report a successful repair of severe traumatic tricuspid regurgitation by PTFE chordal replacement and ring annuloplasty. A 64-year-old man with multiple trauma was referred to our department because of cardiomegaly on chest roentgenogram. Echocardiography showed moderate amount of pericardial effusion and severe tricuspid regurgitation with rupture of anterior papillary muscle. But he experienced progressive dyspnea, and chest roentgenogram showed pro ressive cardiomegaly. He underwent operation 4 months after trauma. The nterior papillary muscle was reinserted, and the valve was repaired by PTFE chordal replacements and ring annuloplasty. Postoperatively, the patient's functional status was improved, and there was trivial tricuspid regurgitation on echocardiographic examination.