• Title/Summary/Keyword: p-method

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Effect of He-Ne laser intravascular irradiation in treatment of cerebral infarction (뇌경색(腦硬塞)에 대(對)한 He-Ne laser 정맥혈관내(靜脈血管內) 조사(照射)의 효과(效果))

  • Park, Yang Chun;Ann, Taek Won;Kim, Dong Hee;Kim, Byeong Tak
    • Journal of Haehwa Medicine
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    • v.9 no.1
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    • pp.387-397
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    • 2000
  • Background : Intravascular Laser Irrardiation of Blood(ILIB) is used in disorder of cerebral and peripheral blood circulation, dysfunction of brain, atherosclerosis etc., but there are little study about ILIB in oriental medicine. We wished to assess the efficacy of ILIB for the treatment of cerebral infarction. Method : The study group comprised 40 patients who arrived at hospital during 48 hours after attack. All patient were divided into two group. The control group was treated with Uhuangcheongsimhuan(牛黃淸心丸), Seonghyangjeonggisan(星香正氣散), acupuncture therapy only, while the ILIB group was treated with above therapy plus 5 days of irradiation of He-Ne Laser(1.8~2.5mW, 50min. per day). In rat model of middle cerebral artery(MCA) occlusion, the control group was not treated, while the ILIB group was treated with irradiation of He-Ne Laser(1.8~2.5mW, 24sec.). Result : 1. Symptom improve scores did not showed significant difference between control and ILIB group. 2. Vasoreactivity of carotid siphon did not showed significant difference between control and ILIB group. 3. Vasoreactivity of radial artery did not showed significant difference between control and ILIB group. 4. PT a-PTT did not showed significant changes between before and after treatment in both group. Fibrinogen significantly increased after treatment in ILIB group(p<0.05)), but it was in normal degree. 5. ILIB showed a significant decrease of brain ischemic area and edema in rat model of middle cerebral artery(MCA) occlusion. Conclusion : These findings suggest that additional treatment of ILIB is not more useful than traditional therapy only in acute cerebral infarction. But ILIB showed potential effect in rat model of MCA occlusion. So further investigation will be necessary.

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An Approach to Determine the Good Seedling Quality of Grafted Tomatoes (Solanum Lycopersicum) Grown in Cylindrical Paper Pot Through the Relation Analysis between DQI and Short-Term Relative Growth Rate (DQI와 단기 상대생장률 분석을 이용한 원통형 종이포트 토마토 접목묘의 우량묘 기준 설정)

  • Seo, Tae Cheol;An, Se Woong;Jang, Hyun Woo;Nam, Chun Woo;Chun, Hee;Kim, Young chul;Kang, Tae Kyung;Lee, Sang Hee
    • Journal of Bio-Environment Control
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    • v.27 no.4
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    • pp.302-311
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    • 2018
  • Using cylindrical paper pot nursery method, three kinds of commercial tomatoes 'Dafnis', 'DOTAERANG DIA' and 'Maescala' were grafted onto a commercial rootstock 'B blocking'. From 10 to 40 days after graft-take, growth traits of seedlings were investigated by 0.5, 1.0 and 2.0S treatments of standard nutrient solution(S) for seedling growth, and top to root ratio(TRR), compactness(CP) and Dickson Quality Index(DQI) were calculated. Two weeks after transplanting of the seedlings under three different night temperature targeting to 10, 15, and $25^{\circ}C$, which were not precisely controlled, the relative growth rate (RGR) was investigated. The quantitative growth traits of grafted seedlings increased with increasing fertilizer concentration, and various range of seedling size could be produced. Compactness and DQI were significantly regressed (Adj $R^2=0.9480$). Short-term RGR after transplanting was higher at 1.0S treatment of standard nutrient solution at the seedling age of 30 days and 40 days after graft-take(DAGT). DQI and RGR were significantly regressed linearly at respective fertigation strength. Specially the diminishing slope of RGR was lower at 1.0S fertigation strength with the increase of DQI than others. The results indicate that DQI could be applied as a quality index of grafted tomato seedlings and the relation analysis between DQI and short-term RGR also could be used to determine the good quality seedlings of grafted tomato grown in cylindrical paper pot.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

The effect of using laser for ceramic bracket bonding of porcelain surfaces (세라믹 브라켓 부착 시 레이저를 이용한 포세린 표면처리 효과)

  • An, Kyung-Mi;Sohn, Dong-Seok
    • The korean journal of orthodontics
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    • v.38 no.4
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    • pp.275-282
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    • 2008
  • Objective: The purpose of this study was to investigate the effect of using laser for ceramic bracket bonding of porcelain surfaces and to compare it with conventional treatment of porcelain surfaces. Methods: Ninety feldspathic porcelain specimens were divided into 9 groups of 10, with each group having different surface treatments performed. Surface treatment groups were orthophosphoric acid, orthophosphoric acid with silane, hydrofluoric acid, hydrofluoric acid with silane, sandblasted, sandblasted with silane, laser etched, laser etched with silane, and glazed surface served as a control group. In the laser etched groups, the specimens were irradiated with 2-watt superpulse carbon dioxide ($CO_2$) laser for 20 seconds. Ceramic brackets were bonded with light-cure composite resin and all specimens were stored in water at $37^{\circ}C$ for 24 hours. Shear bond strength was determined in megapascals (MPa) by shear test at 1 mm/minute crosshead speed and the failure pattern was assessed. For statistical analysis, one-way ANOVA and tukey test were used. Results: Statistical analysis showed significant differences between the groups. The HFA + S group showed the highest mean shear bond strength ($13.92{\pm}1.94\;MPa$). This was followed by SB + S ($10.16\;{\pm}\;1.27\;MPa$), HFA ($10.09\;{\pm}\;1.07\;MPa$), L + S ($8.25\;{\pm}\;1.24\;MPa$), L ($7.86\;{\pm}\;0.96\;MPa$), OFA + S ($7.22\;{\pm}\;1.09\;MPa$), SB ($3.41\;{\pm}\;0.37\;MPa$), OFA ($2.81\;{\pm}\;0.37\;MPa$), G ($2.46\;{\pm}\;1.36\;MPa$), Bond failure patterns of HFA and silane groups, except L + S, were cohesive modes in porcelain while adhesive failure was observed in the control group and the rest of the groups. Conclusions : A 2-watt superpulse $CO_2$ laser etching of porcelain surfaces can provide a satisfactory result for porcelain surface treatment for ceramic bracket bonding. Laser irradiation may be an alternative conditioning method for the treatment of porcelain surfaces.

Synthesis of ceramic particles by hydrothermal method (수열법에 의한 세라믹분말 합성)

  • 김판채;최종건
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • 1996.06b
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    • pp.219-222
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    • 1996
  • 수열법은 밀폐용기중에서 10$0^{\circ}C$이상의 가열, 가압된 수용액이 반응에 관여하는 것으로써, 수정, CaCO3, AlPO4, GaPO4 등과 같은 단결정의 육성 뿐만 아니라 균일분산계로부터 균일한 결정성의 미립자 합성에도 폭넓게 이용되고 있다. 세라믹분말의 합성에 있어서, 이 방법은 특히 형상, 입자크기의 제어가 용이할 뿐만 아니라 고상법, 졸-겔법, 공침법에서와 같은 열처리, 분쇄과정이 필요없기 때문에 고순도의 초미립자를 얻을 수 있는 장점이 있다. 근년 미국, 일본에서는 수열법을 이용한 유전, 압전체 등 세라믹분말의 일부가 공업적인 규모로 대량 생산되고 있다. 그러나 이에 대한 국내 기술은 아직 초기단계에 이르고 있는 실정이다. 따라서 본 연구실에서는 수열법에 의한 단결정 육성 (예; 자수정, CaCO3, AlPO4, GaPO4, KTP, Emerald 등), 박막제조 (예; GaP, PbTiO3, BaTiO3 등), 정제 (고령토, 장석, 도석 등), 원석처리 (진주, 인공 emerald, 비취 등) 그리고 각종 세라믹분말의 합성 등과 같은 다양한 기반기술의 축적과 동시에 공업화에 대응한 수열장치를 위하여 반응용기의 대형화, 엄밀한 밀폐방식, 실용적인 수열조건 등을 개발해 오고 있다. 본 발표에서는 현재까지의 연구개발 내용 중에서 결정성 미립자에 관련한 세라믹분말의 합성에 대한 일부의 결과들을 보고한다. 일반적으로 수열장치는 전기로, 반응용기, 온도 및 압력제어계 등을 기본으로 하고 있으며 시판용의 대부분이 교반기가 부착된 수직형 (vertical type)이다. 이와 같은 방식에 있어서는 엄밀한 밀폐가 곤란, 반응온도의 한계성 (25$0^{\circ}C$ 이하), 증진율의 한계성 (소량생산) 등과 같은 점이 있기 때문에 본 연구실에서는 개폐식 전기로내에 엄밀한 밀폐가 가능한 수평식(horizontal type)의 반응용기를 채택한 뒤 이를 회전 또는 시이소(seesaw)식으로 움직일 수 있도록 하여 연속공정화, 온도구배의 자율조절 그리고 보다 저온에서도 인위적인 이온의 확산을 효율적으로 유도할 수 있도록 하였다. 이와 같은 방식은 기존의 방식과 비교하여 반응용기 내에 응집현상과 미반응물이 존재하지 않으며 또한 단분산으로 결정성 미립자를 대량적으로 얻을 수 있는 장점이 있었다. 다음은 이상과 같이 본 연구실에서 자체 개발한 수열장치를 이용하여 PbTiO3, (Pb,La)TiO3Mn, BaTiO3, ZnSiO4:Mn, CaWO4 등과 같은 세라믹분말에 대한 합성 실험의 결과이다. 압전성, 초전성이 우수한 PbTiO3 및 (Pb,La)TiO3:Mn 분말의 수열합성은 PbO, TiO2, La2O3 등의 분말을 출발원료로 하여 합성도도 25$0^{\circ}C$부근의 알카리성 용액중에서 결정성 PbTiO3 및 (Pb,La)TiO3:Mn 미립자를 단상으로 얻었으며 입자의 형상 및 크기는 합성온도와 수열용매의 종류에 의존하였다. 유전체로서 폭넓게 응용되고 있는 BaTiO3 분말은 Ba(OH)2.8H2O, TiO2와 같은 최적의 출발원료를 선택함으로써 15$0^{\circ}C$ 부근의 저온영역에서도 용이하게 합성할 수 있었다. 특히 본 연구에서는 수용성인 Ba(OH)2.8H2O를 사용함으로써 host-guest적인 반응을 유도시키는데 있어 물의 가장 실용적이고 효과적인 수열용매임도 알았다. ZnSiO4:Mn, CaWO4, MgWO4와 같은 형광체 분말은 공업적으로 고상반응 또는 습식법에 의해 얻어지고 있으나 이들 방법에 있어서는 분쇄공정으로 인한 형광특성의 저하와 같은 문제점이 있다. 따라서 본 연구에서는 수열법을 이용하여 이들 화합물의 합성을 시도하였으며 그 결과 합성온도 30$0^{\circ}C$ 부근의 알칼리성 용액중에서 수열적으로 얻어짐을 알았다. 여기서의 합성분말을 이용하여 실제 조명램프로 제조한 결과 녹색, 청색 발광용 형광체로서 우수한 형광특성을 나타내었다. 천연에서 소량 산출되고 있는 고가의 (Li,Al)MnO2(OH)2:Co 분말은 도자기의 전사지용 청색안료로써 이용되고 있다. 본 연구실에서는 LiOH.H2O, Al(OH)3, MnO2 등의 분말을 출발원료로 하고 24$0^{\circ}C$ 온도 부근 그리고 물을 수열용매로 하여 천연산에 필적하는 (Li,Al)MnO2(OH)2:Co 분말을 인공적으로 합성하였다.

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Revisiting the cause of unemployment problem in Korea's labor market: The job seeker's interests-based topic analysis (취업준비생 토픽 분석을 통한 취업난 원인의 재탐색)

  • Kim, Jung-Su;Lee, Suk-Jun
    • Management & Information Systems Review
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    • v.35 no.1
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    • pp.85-116
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    • 2016
  • The present study aims to explore the causes of employment difficulty on the basis of job applicant's interest from P-E (person-environment) fit perspective. Our approach relied on a textual analytic method to reveal insights from their situational interests in a job search during the change of labor market. Thus, to investigate the type of major interests and psychological responses, user-generated texts in a social community were collected for analysis between January 1, 2013 through December 31, 2015 by crawling the online-community in regard to job seeking and sharing information and opinions. The results of topic analysis indicated user's primary interests were divided into four types: perception of vocation expectation, employment pre-preparation behaviors, perception of labor market, and job-seeking stress. Specially, job applicants put mainly concerns of monetary reward and a form of employment, rather than their work values or career exploration, thus youth job applicants expressed their psychological responses using contextualized language (e.g., slang, vulgarisms) for projecting their unstable state under uncertainty in response to environmental changes. Additionally, they have perceived activities in the restricted preparation (e.g., certification, English exam) as determinant factors for success in employment and suffered form job-seeking stress. On the basis of these findings, current unemployment matters are totally attributed to the absence of pursing the value of vocation and job in individuals, organizations, and society. Concretely, job seekers are preoccupied with occupational prestige in social aspect and have undecided vocational value. On the other hand, most companies have no perception of the importance of human resources and have overlooked the needs for proper work environment development in respect of stimulating individual motivation. The attempt in this study to reinterpret the effect of environment as for classifying job applicant's interests in reference to linguistic and psychological theories not only helps conduct a more comprehensive meaning for understanding social matters, but guides new directions for future research on job applicant's psychological factors (e.g., attitudes, motivation) using topic analysis.

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The Effect of Vitamin E on the Composition of inflammatory Cells in Alveoli after Paraquat Intoxication in Rats (Paraquat에 의한 급성 폐손상에서 Vitamin E처치가 기관지폐포 세척액내 세포조성에 미치는 영향)

  • Song, Kwang-Seon;Lee, Won-Yeon;Cho, Do-Yeun;Yong, Suk-Joong;Shin, Kye-Chul
    • Tuberculosis and Respiratory Diseases
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    • v.44 no.6
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    • pp.1332-1342
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    • 1997
  • Background : Acute pulmonary injury by paraquat are caused by multiple mechanisms including direct injury with oxygen free radicals and several mediators released from inflammatory cells. In order to clarify whether vitamin E could reduce tissue damages induced by intraperitoneal administration of paraquat and to investigate the pathogenetic mechanisms of paraquat-induced pulmonary injury, vitamin E as a free radical scavenger was administered. Method : Rats were divided into three groups (group 1 : control, group 2 : paraquat treated group, group 3 : paraquat and vitamin E treated group). Animals were sacrificed on day 1, day 2, day 3, and day 8 after the administration of saline, paraquat, or paraquat/vitamin E. Results : Treatment with vitamin E decreased the death rate of rats treated with paraquat. Comparing with control group ($1.37{\times}10^6/ml$), mean total cell counts recovered from the lavage fluid from animals treated with paraquat($1.65{\times}10^6/ml$) were increased(p=0.06). Magnitudes of increment of the total cell counts on the Day 8 in the vitamin E treated group were smaller than those of the animals treated with paraquat alone. The neutrophils began to appear in significant amounts in the lavage fluid on Day 8 after the administration of paraquat(37.0+12.7%). A significant decreasing neutrophil concentration at Day 8 was observed in the paraquat/vitamin E treated group(20.6+13.4%). Histologically the degree of pulmonary fibrosis was most prominent in the paraquat treated group while diffuse alveolar damage was continuously observed in the paraquat/vitamin E treated group and extensive interstitial lymphocytic infiltration was seen in the paraquat/vitamin E treated group. The paraquat/vitamin E treated group showed the less histologic changes. Conclusion : In this study vitamin E acting as a scavenger of neutrophil-derived free radicals and suppressant of lipid peroxidation, seemed to be the effective antioxidant in the inhibition of paraquat-induced pulmonary injury.

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The Bronchoalveolar Lavage Fluid Cell Analysis with Normal Lung and Unaffected Side Lung of Patients with Minor Symptoms or Radiologic Abnormalities (경미한 호흡기질환 환자에서 정상 및 건측 폐에서의 기관지폐포 세척액내 세포 분포에 관한 연구)

  • Kim, Byung-Il;Cho, Chul-Ho;Kang, Shin-Wook;Cheon, Seon-Hee;Jang, Sang-Ho;Lee, Jang-Hoon;Chang, Joon;Kim, Sung-Kyu;Lee, Won-Young
    • Tuberculosis and Respiratory Diseases
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    • v.38 no.2
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    • pp.155-163
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    • 1991
  • Bronchoalveolar lavage had been done as the treatment of some diseases such as alveolar proteinsois, bronchiectasis, and severe asthma to remove excessive secretion or mucus. But in the recent decade it has been done as a diagnostic method and a tool to understand and evaluate the pathophysiology of diffuse interstitial lung diseases such as sarcoidosis, pneumoconiosis and hypersensitivity pneumonitis. To analyse the bronchoalveolar fluid, it might be useful to have a standard reference (especially cell counts and differetial count of the cells from bronchoalveolar lavage fluid) of normal person. But it is difficult to study the normal volunteers. We investgated the bronchoalveolar lavage fluid of 48 patients (28 nonsmokers, 20 smokers) who visited Severance Hospital because of minor pulmonary symptoms such as cough and sputum. They did neither complain of dyspnea nor cyanosis, and had normal or unilateral minor lesion on physical examination and chest X-ray. We analysed the recovery rate, viability, total cell count and differential count of the cells in fluid obtained by bronchoalveolar lavage. The following results were obtained: 1) Age ranged from 17 to 72 years-old with the mean age of 36.7; there was no difference of age between the nonsmoker and the smoker gorup. Male to female ratio was 2.43:1 for total group, 1.15:1 for nonsmokers, and 19:1 for smokers. 2) The diagnoses of the patients were undetermined in 41.9%, healed pulmonary tuberculosis in 37.5%, laryngitis or pharyngitis in 10.4% and others in 10.4%. 3) Total cell number of the recovered fluid by bronchoalveolar lavage was significantly higher in male[$9.6{\pm}6.2({\times}10^6)$] than in female[$5.1{\pm}3.0({\times}10^6)$](p<0.05), and there was no significant difference in the total cell number between the smokers and nonsmokers [$9.3{\pm}5.8({\times}10^6)$ vs $7.5{\pm}5.8({\times}10^6)$]. 4) The differential count of the cells from bronchoalveolar lavage fluid had no difference between the nonsmokers and the smokers. 5) There was no correlation between the total cell count and smoking or age. 6) In the smoker group, there was no correlation between the amount of smoking and the total cell count of the bronchoalveolar fluid. In conclusion, it should be careful to regard the patients with symptoms or minor radiologic abnormalities as a control group in bronchoalveolar lavage study and further study of cell analysis in bronchoalveolar lavage will be needed between smoker and nonsmoker in the male and female healthy people.

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A Study on the Influence of Finishing and Polishing Methods on the Gap between Denture Base Resin and Soft Liner (의치의 마무리와 연마법이 의치상 레진과 연성 이장재 간의 공극에 미치는 영향에 관한 연구)

  • Jung, Seung-Hwan;Lee, Joon-Seok
    • Journal of Dental Rehabilitation and Applied Science
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    • v.24 no.4
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    • pp.325-335
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    • 2008
  • The junction between resilient denture liner and the denture base is difficult to finish and polish due to difference of the physical property of the materials. Gaps tend to be formed during finishing and polishing procedures. The purpose of this study was measuring the width of junctional gap between $Molloplast-B^{(R)}$ and denture base material after finishing and polishing procedure, and evaluating the effect of method and direction on gap width. $Molloplast-B^{(R)}$ was processed (according to the manufacturer's instruction) against Lucitone $199^{(R)}$ acrylic resin. 50 specimens were fabricated with a raised center section. All of specimens were examined and photographed with a stereoscopic microscope(x120), and the largest gap along the junction of $Molloplast-B^{(R)}$ and acrylic resin on each specimen was measured. One-way analysis of variance(ANOVA) and independent t-test at 95% confidence level were used to analyze the data and to compare groups. The results of this study were as follows. In comparison with finishing tools, the gap width was the largest in $Molloplast^{(R)}$-Cutter and the smallest in FSQ-cross cut bur. There was statistically significant difference between FSQ-cross cut bur and $Molloplast^{(R)}$-Cutter(p<0.05). There was no significant difference in gap width between the direction of polishing. The mean value of gap width was the smallest in case of no polishing, and the largest in case of polishing with pumice & tin oxide. There was statistically significant difference between pumice and pumice & tin oxide. From the results, it is concluded that the use of $Molloplast^{(R)}$-Cutter in clinic need serious consideration even though it has good cutting ability. Further careful study is needed for finishing and polishing methods for decreasing gap width in junction of two materials.

The Effect of Packing Method of Relining Material on the Flexural Strength of Denture Base Resin (첨상용 레진의 성형법이 의치상의 굴곡강도에 미치는 영향)

  • Kim, Min-Chul;Kim, Yu-Lee
    • Journal of Dental Rehabilitation and Applied Science
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    • v.27 no.2
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    • pp.197-207
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    • 2011
  • The study aimed at examining how different reline resins affect flexural strength and flexural modulus of denture base. A total of 80 specimens ($64{\times}10{\times}3.3$ mm, according to ISO 1567:1999) of heat-polymerized resin, 40 specimens for (Lucitone199(Dentsply Int., NewYork, USA), SR Ivocap(Ivoclar AG, Schaan, Liechtenstein)) respectively, were polymerized according to the manufacturer's instructions and divided into eight groups(n = 10). Control group specimens remained intact. Specimens in the other groups were abraded on both sides to 2 mm thickness, and were relined in 1.3 mm thickness with 3 types of resins (Lucitone199(Dentsply), SR Ivocap(Ivoclar), and Rebase II(Tokuyama Co., Ltd, Tokyo, Japan)). All specimens were preserved in distilled water at $37^{\circ}C$ for 50 hours, and then were subjected to flexural strength testing in a universal testing machine using 3-point loading. A crosshead speed of 5 mm/min was used, and the distance between the supports was 50 mm. Data analyses included one-way analysis of variance(ANOVA) and the Tukey Honestly Significant Difference test (p=.05). Both heat-polymerized resin groups and auto-polymerized resin groups showed statistically low flexural strength and flexural modulus than control groups. Specimens relined with Lucitone 199 showed significantly higher flexural strength and flexural modulus than those relined with SR-Ivocap. Specimens relined with auto-polymerized resin showed significantly lower flexural strength and flexural modulus than those relined with heat-polymerized resin. Relining with heat-polymerized resins showed superior mechanical properties to relining with an auto-polymerized resin. Relining with the same heat-polymerized resin as the denture base does not affect mechanical properties of a denture. Lucitone199 using a compression-mould technique resulted in the highest flexural strength.