• Restorative Dentistry and Endodontics
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• 제43권4호
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• pp.40.1-40.10
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• 2018

Objectives: This study evaluated the microtensile bond strength (${\mu}TBS$) of polymer-ceramic and indirect composite resin with 3 classes of resin cements. Materials and Methods: Two computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated polymer-ceramics (Enamic [ENA; Vita] and Lava Ultimate [LAV; 3M ESPE]) and a laboratory indirect composite resin (Gradia [GRA; GC Corp.]) were equally divided into 6 groups (n = 18) with 3 classes of resin cements: Variolink N (VAR; Vivadent), RelyX U200 (RXU; 3M ESPE), and Panavia F2 (PAN; Kuraray). The ${\mu}TBS$ values were compared between groups by 2-way analysis of variance and the post hoc Tamhane test (${\alpha}=0.05$). Results: Restorative materials and resin cements significantly influenced ${\mu}TBS$ (p < 0.05). In the GRA group, the highest ${\mu}TBS$ was found with RXU ($27.40{\pm}5.39N$) and the lowest with VAR ($13.54{\pm}6.04N$) (p < 0.05). Similar trends were observed in the ENA group. In the LAV group, the highest ${\mu}TBS$ was observed with VAR ($27.45{\pm}5.84N$) and the lowest with PAN ($10.67{\pm}4.37N$) (p < 0.05). PAN had comparable results to those of ENA and GRA, whereas the ${\mu}TBS$ values were significantly lower with LAV (p = 0.001). The highest bond strength of RXU was found with GRA ($27.40{\pm}5.39N$, p = 0.001). PAN showed the lowest ${\mu}TBS$ with LAV ($10.67{\pm}4.37N$; p < 0.001). Conclusions: When applied according to the manufacturers' recommendations, the ${\mu}TBS$ of polymer-ceramic CAD/CAM materials and indirect composites is influenced by the luting cements.

• 대한치과보철학회지
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• 제38권6호
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• pp.782-790
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• 2000

The mainly used polymeric material for the denture is PMMA because of its cost and easiness to handle. So it was widely used material among dentists for past decades. But the acrylic-based denture materials have several common weak points such as shrinkage after curing and lack of strength. In order to solve these problems, we adapted one of hybrid system using acrylic polymer and vinyloligosilsesquioxane(POSS). POSS, which is a well known expandable monomer during polymerization process, may eventually suppress volumetric shrinkage. And the hybrid system makes it possible for the polymer to be stable in various severe conditions. Eight different kinds of samples were designed and synthesized. Each samples were characterized with dynamic mechanical analyser(DMA) to confirm their thermodynamic properties, fractured to analyze the cross-sectional morphology of the samples. And elongation, flexural and impact tests were also executed to evaluate the mechanical properties of the samples. From the results, hybrid composites had well defined crosslinked network structure compared to the widely used denture materials, and the mechanical strength improved without changing any surface condition as increment with POSS ratio in hybrid system. Fractured morphology showed homogeneous surfaces in spite of mutli component system, therefore we can conclude that the adoption of the POSS brought the reinforcement of the denture resin.

• Elastomers and Composites
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• 제47권2호
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• pp.141-147
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• 2012

실리콘 수지는 소수성이 강한 고분자이기 때문에 수분을 흡수하는 기능이 전혀 없다. 하지만 고흡수성 수지(Super Absorbent Polymer)를 첨가제로 사용하면 기존의 실리콘보다 월등한 흡수성을 갖게 된다. 본 연구에서는 무정형 형태의 입자 크기가 다른 아크릴계 고흡수성 수지 3가지를 선택하여 배합비를 설정하고 2액형 타입의 의료용 실리콘 소재에 적용해서 수분을 흡수하는 기능을 갖는 새로운 실리콘 소재를 개발하였다. 고흡수성 수지의 첨가에 의한 실리콘 수지의 제조시 입자 사이즈와 함량을 달리하면서 인장, 인열, 압축, 경도에 대한 기계적 물성 변화를 알아보았으며, 시간에 따른 실리콘 수지의 흡수성을 측정하였다. 또한 전자 현미경을 통해 고흡수성 수지의 입자형태와 실리콘 수지와의 분포도를 관찰하였다.

• Tribology and Lubricants
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• 제38권6호
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• pp.255-260
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• 2022

This research presents tetrahedral amorphous (ta-C) coating on the artificial tooth for improving the durability and functionality (esthtics, foreign body of tooth) by filtered cathodic vacuum arc (FCVA). A differentiated coating method is required for a ta-C coating on polymer owing to the low melting point of the polymer, inter-facial adhesion, low friction, and non-conductivity. Herein, ta-C coating is applied below 50℃, and the potential difference of the carbon plasma drawn to the substrate was controlled by applying a positive duct bias voltage without using a substrate bias voltage. Consequently, the ta-C coating with a thickness of 70nm using the duct bias condition of 20V with the highest plasma intensity satisfies the esthetics of the artificial tooth and had a 5B level of inter-facial adhesion. In addition, the composite hardness of ta-C/polymer is 380 MPa, and correlations with esthetics, sp³ bonding, and mechanical properties. The friction coefficient (CoF) of the ta-C coating in a water-lubricated environment is 0.07, showing a six-fold reduction in CoF compared with that of a polymer.

• The Journal of Advanced Prosthodontics
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• 제8권6호
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• pp.504-510
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• 2016

PURPOSE. Polyamide polymers do not provide sufficient bond strength to auto-polymerized resins for repairing fractured denture or replacing dislodged denture teeth. Limited treatment methods have been developed to improve the bond strength between auto-polymerized reline resins and polyamide denture base materials. The objective of the present study was to evaluate the effect of surface modification by acetic acid on surface characteristics and bond strength of reline resin to polyamide denture base. MATERIALS AND METHODS. 84 polyamide specimens were divided into three surface treatment groups (n=28): control (N), silica-coated (S), and acid-treated (A). Two different auto-polymerized reline resins GC and Triplex resins were bonded to the samples (subgroups T and G, respectively, n=14). The specimens were subjected to shear bond strength test after they were stored in distilled water for 1 week and thermo-cycled for 5000 cycles. Data were analyzed with independent t-test, two-way analysis of variance (ANOVA), and Tukey's post hoc multiple comparison test (${\alpha}=.05$). RESULTS. The bond strength values of A and S were significantly higher than those of N (P<.001 for both). However, statistically significant difference was not observed between group A and group S. According to the independent Student's t-test, the shear bond strength values of AT were significantly higher than those of AG (P<.001). CONCLUSION. The surface treatment of polyamide denture base materials with acetic acid may be an efficient and cost-effective method for increasing the shear bond strength to auto-polymerized reline resin.

• Restorative Dentistry and Endodontics
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• 제39권3호
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• pp.155-163
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• 2014

Objectives: Light-curing of resin-based materials (RBMs) increases the pulp chamber temperature, with detrimental effects on the vital pulp. This in vitro study compared the temperature rise under demineralized human tooth dentin during light-curing and the degrees of conversion (DCs) of three different RBMs using quartz tungsten halogen (QTH) and light-emitting diode (LED) units (LCUs). Materials and Methods: Demineralized and non-demineralized dentin disks were prepared from 120 extracted human mandibular molars. The temperature rise under the dentin disks (n = 12) during the light-curing of three RBMs, i.e. an Ormocer-based composite resin (Ceram. X, Dentsply DeTrey), a low-shrinkage silorane-based composite (Filtek P90, 3M ESPE), and a giomer (Beautifil II, Shofu GmbH), was measured with a K-type thermocouple wire. The DCs of the materials were investigated using Fourier transform infrared spectroscopy. Results: The temperature rise under the demineralized dentin disks was higher than that under the non-demineralized dentin disks during the polymerization of all restorative materials (p < 0.05). Filtek P90 induced higher temperature rise during polymerization than Ceram.X and Beautifil II under demineralized dentin (p < 0.05). The temperature rise under demineralized dentin during Filtek P90 polymerization exceeded the threshold value ($5.5^{\circ}C$), with no significant differences between the DCs of the test materials (p > 0.05). Conclusions: Although there were no significant differences in the DCs, the temperature rise under demineralized dentin disks for the silorane-based composite was higher than that for dimethacrylate-based restorative materials, particularly with QTH LCU.

• 통합자연과학논문집
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• 제6권1호
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• pp.1-7
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• 2013

Polyurethane resin containing isocyanate is marked by excellent tensile and mechanical strengths and this test aims to gauge its applicability as a medical high polymer. Tris [2-(acryloyloxy)ethyl]isocyanurate and hexamethylenediisocyanate were added to a basic mixing ratio of HEMA (2-hydroxyethyl methacrylate), MMA (methyl methacrylate), NVP (n-vinyl-2-pyrrolidone) and crosslink agent, EGDMA (ethylene glycol dimethacrylate) with increasing proportions and copolymerized respectively. Also, the basic physical properties of the polymerized high polymers including refraction rate, tensile strength, light transmission and water content were measured to confirm that they are appropriate as hydrogelcontact lenses. After measuring the physical properties of high performance polymers produced by adding tris [2-(acryloyloxy) ethyl]isocyanurate, it was found that the average tensile strengths of sample TRIS1 to TRIS10 were between 0.285 and 0.612 kgf, while the average values of refractive index were ranged from 1.441 to 1.449 with water content from 30.00 to 37.35%.The measurement of physical properties of the copolymers generated by adding hexamethylenediisocyanate showed that the average tensile strength of sample HEXA1 to HEXA10 ranged from 0.267 to 1.742 kgf, the refractive index ranged from 1.443 to 1.475 and water contents were in the range of 21.22 to 35.58%. In all combinations the transmission rates satisfied the transmittance of general hydrogel contact lenses. From theresults, it is possible to conclude that the produced copolymers can be used as contact lens materials with excellent tensile strength.

• 한국융합학회논문지
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• 제9권12호
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• pp.99-106
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• 2018

의료방사선 방어를 위해 사용되는 차폐 시트의 제조과정에서 인장강도를 유지하면서 차폐 재료의 충전율을 높여 차폐 성능을 향상시키는 방안을 제시하고자 한다. 본 연구에서 제안된 개질제는 고분자 수지재료와의 융합에 있어서 분자량을 높여 재료의 친화성을 높이는 역할을 수행한다. 차폐시트의 산화텅스텐의 충전율과 인장강도, 차폐 성능 등을 평가하였다. 공정과정에서 개질제는 분자량과 밀도를 증가시켰고, 성형 과정에서 퍼짐 형상이 적용되었고, 성능 향상과 재료와의 친화성, 인장강도를 유지하기 위해 사용된 개질제 PMMA는 20%를 혼합할 경우 가장 우수한 효과를 얻을 수 있다. 본 연구에서 제시된 재료의 융합과 개질제를 통해 차폐시트의 대량생산이 가능하며, 향후 경량의 차폐복 제작에 기여할 것입니다.

• 한국응용과학기술학회지
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• 제35권3호
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• pp.935-939
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• 2018

3D프린팅 기술은 산업적 응용을 넘어서 기계 설비 및 각종 장비의 부품생산뿐만 아니라 의료, 식품, 패션에 이르기까지 많은 시제품들의 개발 및 연구가 진행되고 있다. 3D 프린팅 기반 기술의 적용사례를 볼 때 정밀도와 제작 속도 측면에서도 다른 산업에 충분이 활용될 수 있는 기술의 개발이 보고되고 있으나, 아직까지는 시제품 위주로 이용되고 있으며, 향후 3D 프린팅 기술은 4차산업혁명과 관련하여 광범위한 분야에서 응용될 수 있는 완성품이나 부품제작에 이용될 것으로 예상된다. 본 연구에서는 탄소나노 재료중 대표적으로 많이 이용되는 환원그래핀 [rGO(reduced graphene oxide)]과 전도성 고분자중 생체 친화적인 특성을 갖는 폴리피롤[Ppy(Polypyrrole)]의 복합체를 생분해성 고분자인 폴리카프로락톤 [PCL(polycaprolactone)]과 혼합하여 3D 프린팅용 전도성 레진을 개발하고자 하였다. 결과로, 폴리피롤과 환원그래핀 각각 5 wt%, 0.75 wt% 에서 최적의 전기적 특성을 나타내었으며, 환원그래핀의 농도에 따른 표면분석에서도 이와 부합하는 결과를 확인 할 수 있었다. 본 연구를 통하여 제조된 전도성 레진은 3D 프린팅 뿐만 아니라, 다른 산업분야의 전자재료에도 적용이 가능할 것으로 사료된다.

• 폴리머
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• 제35권1호
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• pp.40-46
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• 2011

The synthesis of well-defined poly(styrene-b-isobutylene-b-styrene) (SIBS) triblock copolymers was accomplished by cationic sequential block copolymerization of isobutylene (IB) with styrene (St) using 1,4-di(2-chloro-2-propyl) benzene (DCC) /$TiCl_4$/2,6-di-tert-butylpyridine(DtBP) as an initiating system in methyl chloride ($CH_3Cl$)/methylcyclohexane(MeChx) (50/50 v/v) solvent mixture at $-80^{\circ}C$. The triblock copolymers exhibited excellent thermoplastic and elastomeric characteristics. Tensile strengths and Shore hardness increased with increasing polystyrene (PS) content, while elongation at break decreased. The blood-compatibility of SIBS was assessed by SEM observation of the platelet adhesion, blood clotting time and haemolysis ratio. The haemolysis ratios were below 5% which met the medical materials standard. The platelet adhesion test further indicated that SIBS block copolymers had a good blood compatibility.