• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.55-58
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• 2003

Segmented polyurethanes have been widely used for various commercial and experimental blood-contacting and tissue-contacting applications such as vascular prostheses, blood pumps, heart valves, pacemaker lead wire insulation, catheters, artificial hearts, and cardiac assist devices due to their generally favorable physical and mechanical properties, as well as fairly good biocompatibility and antithrombogenicity characteristics. (omitted)

• The Korean Journal of Pharmacology
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• v.5 no.1
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• pp.35-38
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• 1969

1.On isolated atrial preparation of frog, effects of sympathomimetic amines were investigated. 2. Isoproterenol, epinephrine, norepinephrine, and phenylephrine produced positive chronotropic and inotropic effects. The relative potencies for the effects of these agents were: isoproterenol > epinephrine> norepinephrine> phenylephrine. Methoxamine had no effects or depressed the atria. 3. Pronethalol antagonized the positive effects of these adrenergic agents competitively. 4. Regitine did not affect the effects of these agents. 5. These data indicate that the adrenergic agents activate the atrial tissue of the frog via stimulation of adrenergic beta-receptor.

• The Journal of the Korean dental association
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• v.13 no.5
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• pp.415-416
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• 1975

1. The author have had a case of class V and class Ⅲ combined carious lesion extended on to root surface of upper right lateral incisor. 2. The patient was 40 years old female. 3. After routine root canal treatment of the tooth, the gingival flap was made by vertical incision on gingival tissue between distal surface of upper right lateral incisor and mesial surface of upper right canine. 4. Cavity preparation and amalgam filling on the carious lesion were performed and the flap was sutured.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.2
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• pp.167-189
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• 1992

Frictional heat produced by cutting tools during dental implantation procedure may destroy the surrounding bone tissue and regenerative capacity and interfere ossointegration by formation of undifferentiated connective tissue. To study the effect of frictional heat according to various rotational speeds on the regenerative capacity of surrounding bone tissue, 13 ITI HS implants (8 mm) were inserted at 4 mongrel dogs. Temperatures were measured using thermocouple located 6 mm below from the marginal crest and 0.5 mm from the periphery of trephine mill during implant bed preparation. After 4 and 9 months, animals were sacrificed and specimens were examined using x-rays and light microscope. Results were as follows: 1. With drill speeds of 300, 800, 2,000, 3,500 rpm and saline irrigation, temperatures of surrounding bone were decreased from $-2.9^{\circ}\;to\;-1.7^{\circ}C$. Temperature rises of $2.0^{\circ}\;and\;2.1^{\circ}C$ were recorded with a drill speed of 5,000 rpm and irrigation. 2. With drill speeds of 800, 3,500, 5,000 rpm and no irrigation, temperatures of surrounding bone rose from $+1.5^{\circ}\;to\;+6.8^{\circ}C$, but maximum temperature was $40^{\circ}C$ at 5,000 rpm. 3. On radiographic examination, bone resorptions were observed at the upper half of implant of 5,000 rpm without irrigation and one case of 5,000 rpm with irrigation. 4. Osseointegration was unsuccessful in cases of 3,500, 5,000 rpm without irrigation due to fibrous connective tissue formation to the outer surface and hollow, but it was successful in a case of 800 rpm without irrigation. 5. Osseointegration was successful in cases of 300, 800, 2,000 and 3,500 rpm with irrigation. But fibrous connective tissue formation was observed at the hollow of implant inserted with 5,000 rpm with irrigation.

• Restorative Dentistry and Endodontics
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• v.21 no.2
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• pp.451-469
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• 1996

The purpose of this study was to investigate the effect of calcium hydroxide and glass ionomer cement fillings on the levels of $LTB_4$ and $LTC_4$ in experimentally inflamed rat dental pulp. The dental pulp in the mandibular incisor of wistar rat was irritated by cutting a 5mm deep hole in the dentin with a twist drill bur of 0.5mm diameter, without cooling. The cavities were filled with calcium hydroxide(light-cured) and glass ionomer cement(light cured). The untreated pulp served as control tissue specimen. After cavity preparations, the rat with or without various treatment were sacrificed in various time by decapitation. The dental pulp tissue were carefully removed and the concentrations of $LTB_4$ and $LTC_4$ were determined by radioimmunoassay. And pulps were examined histologically to observe inflammatory feature. The result were obtained as follows : 1. The inflammatory features of pulps were observed microscopically in all experimental groups. And degree of inflammation was decreased with time. 2. The concentrations of $LTB_4$ and $LTC_4$ for all experimental groups were significantly higher than those for control group 6 hours after cavity preparation(p<0.05). 3. The group filled with calcium hydroxide was the lowest, and the group filled with glass ionomer cement, the group of irritation in that order showed increased concentrations of $LTB_4$ and $LTC_4$ 6 hours after cavity preparation. In the concentrations of $LTB_4$, significant differences among 3 groups were noted(p<0.05). 4. The group filled with calcium hydroxide was the lowest, and the group filled with glass ionomer cement, the group of irritation in that order showed increased concentrations of $LTB_4$ and $LTC_4$ 24 hours after cavity preparation. And there were statistically significant difference in concentrations of $LTB_4$ between the group of irritation and the group filled with calcium hydroxide(p<0.05). 5. The group filled with calcium hydroxide was the lowest, and the group filled with glass ionomer cement, the group of irritation in that order showed increased concentrations of $LTB_4$ and $LTC_4$ 48 hours after cavity preparation. But no statistically difference was found (p>0.05). 6. The concentrations of $LTB_4$ and $LTC_4$ in all experimental groups were highest level at 6 hour after experiment and decreased as time progresses(correlation coefficient>0.8).

• Journal of Periodontal and Implant Science
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• v.25 no.2
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• pp.301-320
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• 1995

The purpose of this study was to evaluate a new biodegradable membrane - atelocollagen as a guided tissue regeneration barrier on the dehiscence defects adjacent to the dental implants. 3 beagle dogs were selected for this study and all the mandibular premolars($P_1,P_2,P_3&P_4$) were extracted. Twelve weeks after the extraction, the edentulous ridges were formed to be placed the titanium plasma-sprayed IMZ implants. Four implant osteotomies were performed on each side of the mandible. The osteotomies were placed facially in the edentulous ridges to approximate an actual dehiscence defect as closely as possible, The standardized dehiscence defects were created 3 mm in width and 4 mm in height by osteotomy. A total 24 implants were placed. e-PTFE, ateloco11agen and $Collatape^{(R)}$ were placed to cover the defects and the one defect served as a control, not covered any membrane. By random selection, three dogs were sacrificed at 2 weeks, 4weeks and 8 weeks after fixation with 3% glutaraldehyde. A week before sacrificing, 8-week dog was infused intravenously with oxy-tetracycline 30mg/kg. The left mandibular blocks were used for full decalcified histologic preparation and the right mandibular blocks were selected for undeca1cified preparation, At 2 weeks, the regenerated bone of e-PTFE and atelocollagen groups appeared to be more dense than other groups and the percentage of bone defect fill was highest for e-PTFE and follwed by ateloco1lagen group. However, the $Collatape^{(R)}$ and control groups showed a little new bone formation. $Collatape^{(R)}$ was almost degraded within 2 weeks. At 4 weeks, the regenerated new bone were much greater and denser than at 2 weeks for e-PTFE and ateloco11agen group. Although a part of atelocollagen bagan to be degraded at the margin and surrounded by foreign body giant cells related to foreign body reaction, it was generally intact and the regenerated new bone was shown much more than at 2 weeks. The amount of new bone in $Collatape^{(R)}$ and control groups at 4 weeks were similar to that of 2 weeks group. At 8 weeks, the regenerated bone was matured and observed along the implant fixture. Direct new bone formation and calcium deposits beneath the e-PTFE were observed. No further bone growth was seen in the $Collatape^{(R)}$ and control groups. In reflected fluoromicrcocopic observation, the osteogenic activity was pronounced between e-PTFE membrane and the old bone. High osteogenic activity was also observed in atelocol1agen group. This study suggested that the ateloco11agen as well as e-PTFE could be used for guided tissue regeneration on dehiscence defects adjacent to the dental implants. But the $Collatape^{(R)}$ was completely resorbed within 2 weeks and was not a suitable membrane for guided bone regeneration.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.11-17
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• 2008

The purpose of this study was to investigate early histological changes and calcitonin gene-related peptide (CGRP) expression in the dental pulp of the rat after Er:YAG laser preparation. Occlusal cavities were prepared in the upper first molars using either Er:YAG laser and conventional bur. At 48 hours after cavity preparation, the teeth were processed for hematoxylin-eosin stain and CGRP immunohistochemistry. The results were as follows : 1. The cavity floor by Er:YAG laser preparation was more irregular shape compared with those by bur preparation and there are some cracks in the directions of dentinal tubules. 2. There were more inflammatory cell infiltration and disruption of odontoblast in the dental pulp by Er:YAG laser preparation in comparison with the dental pulp by bur preparation. 3. CGRP expression in the pulp tissue by both Er:YAG laser and bur preparations were increased and higher than in the normal pulp. The expression pattern of CGRP was more strong in the pulp by Er:YAG laser preparation. These results indicate that Er:YAG laser is useful in the operative dentistry such as caries removal and cavity preparation if properly applied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.3794-3801
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• 2010

This study evaluated the linear dimensional changes with the factor of time and thickness using of three commercially available tissue conditioners (Coe-Comport, Visco-Gel, Soft-Liner). The thickness of materials were changed (1.5mm, 3.0mm) and the percentage changes in dimension were measured at 1h(baseline), 12h, 24h, 3 days and 7days after specimen preparation. The obtained data were analyzed by ANOVA with the SAS/PC statistical package. From the results, large differences appear between the various tissue conditioners. The results suggested that the period recommended for forming functional impression would be 36h to 3days after insertion in the mouth. Depending on the type of tissue conditioner over time, as there were significant differences in the elastic change(p<0.05). Tissue conditioner of the 1.5mm, 3.0mm thickness were significantly different by the dimensional stability(p<0.05). Elastic deformation of the ideal itself, and resilient when compared only the look, Visco-Gel 3.0mm group, stability was the most stable volume. In addition, it is important to select tissue conditioners suitable for functional impression because of the wide range of dimensional stability among the materials.

• Archives of Plastic Surgery
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• v.36 no.2
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• pp.127-134
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• 2009

Purpose: Adipose tissue injection as a free graft for the correction of soft - tissue deficiency or depression deformity is a widespread procedure in plastic surgery. This study is to analyze the changes and viability of cryopreserved adipose tissue and to find out efficient long - term storage period. Methods: After centrifugation of aspirated abdominal tissues, $10m{\ell}$ of packed Adipose tissue were freezed at $-20^{\circ}C$. For 2, 4, 6, 8 months, each frozen samples were taken and injected into scalp of SCID mice. After 15 weeks, injected Adipose tissue were sampled and analyzed at 2 months interval. We compared and analyzed each group about the weight of the injected fat, histologic impressions, activity of mitochondria, size of a fat cell and rate of survival. Results: Significant weight changes were observed in cryopreservation for 2 months(p<0.05). Histologic changes were observed, independent of the freezing period with H - E stain. Among cryopreservations for 2, 4, 6 months, no significant change were observed. The reduction of mitochondrial enzymatic activity was observed independent of time interval but activity of mitochondrial dehydrogenase was reduced less than 50% in MTT assay. Conclusion: Freezing in $-20^{\circ}C$ for 6 months has no adverse effect to Adipose tissue, but fragile adipocytes, damaged cell membrane during harvesting procedure, were disrupted within 1 - 2 month and the maximum volume reduction were followed less than 2 months. These results demonstrate that tissue preparation cells without membrane damage have the greatest viability level and cryopreservation less than 2 months has great volume effect and cryopreservation for 6 months has stable volume effect.

• Polymer(Korea)
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• v.29 no.2
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• pp.198-203
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• 2005

Melt extrusion foaming process for the preparation of poly(L-lactic acid) (PLLA) scaffolds was carried out and the effects of foaming conditions on the pore structure of PLLA scaffolds and their mechanical properties were investigated. The porosity and mechanical properties of fabricated scaffolds were compared with the scaffolds obtained from the salt leaching method as well. It was found that the optimum pore structure was achieved when the PLLA melt was kept in extruder for the maximum decomposition time of blowing agent. In order to maintain the proper scaffolds structure, the blowing agent content should be less than $10\;wt\%$. It can be concluded that melt extrusion foaming process allows for the production of scaffold having higher mechanical properties with reasonable pore size and open cell structure for hard tissue regeneration even though it has less porosity than scaffolds made by salt leaching process.