• 대한치과보철학회지
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• 제45권1호
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• pp.98-106
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• 2007

Statement of problem: Current tendencies of the implant macrodesign are tapered shapes for improved primary stability, but there are lack of studies regarding the relationship between the implant macrodesign and primary stability. Purpose: The purpose is to investigate the effect of implant macrodesign on the implant primary stability by way of resonance frequency analysis in the bovine rib bones with different kinds of quality. Material and method: Fifty implants of 6 different kinds from two Korean implant systems were used for the test. Bovine rib bones were cut into one hundred pieces with the length of 5 cm. Among them forty pieces of rib bones with similar qualities were again selected. For the experimental group 1, the thickness of cortical part was measured and 20 pieces of rib bones with the mean thickness of 1.0mm were selected for implant placement. For the experimental group 2, the cortical parts of the remaining 20 pieces of rib bones were totally removed and then implants were placed on the pure cancellous bone according to the surgical manual. After placement of all implants, the implant stability quotient(ISQ) was measured by three times, and its statistical analysis was done. Results: There are statistically significant differences in ISQ values among 4 different kinds of Avana system implants in the experimental group 2. For the experimental group 1, Avana system implants showed significantly different ISQ values, but when differences in the thickness of cortical parts were statistically considered, did not show any significant differences in ISQ values. Among Oneplant system implants, there are no significant differences in ISQ values for the experimental group 2 as well as for the experimental group 1. Conclusion: Within the limits of this study, bone quality and implant design have some influences on the primary stability of implants. Especially in the bone of poor quality, tapered shape of implants are more favorable for the primary stability of implants.

• 대한치과보철학회지
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• 제43권4호
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• pp.519-527
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• 2005

Statement of problem : There are many articles that showed that the magnetism affected the bone formation around titanium implant. It means that a proper magnetism made the osseointegration improved around the implant. So after additional research on the other effect of magnetism on bone formation in implant therapy, we can conclude its possibility of clinical application on implant treatment. Purpose: The purposes of this study were to find out the intensity of magnetic field where magnetism in the titanium implant specimen inserted into the bone could affect the bone formation, and to discover the possibility of clinical application in the areas of dental implants and bone grafts. Material and method: Ten adult male rabbits(mean BW 2Kg) were used in this study. Titanium implant specimens were surgically implanted on the mesial side of the tibia of rabbits. Neodymium magnets(Magnedisc 500, Aichi Steel Corp. Japan) were placed into the implants of experimental group except control group, just after placement of the titanium implants. At 2, 4 and 8 weeks after the surgery, the animals were sacrificed, specimens were obtained and stained with Hematoxylin-Eosin for light microscopic evaluation and histomorphometric analysis. Conclusion : The results were as follows: 1. In radiographic findings, increased radiopacity downward from crestal bone was observed along the titanium implant specimen at experimental period passed by 2, 4, and 8 weeks in both control and experimental group. 2. In histoiogic findings, increased new bone formation was shown in both control and experimental group through the experiment performed for 2, 4, and 8 weeks. More new bone formation and bone remodeling were shown in experimental group. 3. In histomorphometric analysis, the bone contact ratios were 11.9% for control group and 38.5% for experimental group (p<0.05).

• 대한치과보철학회지
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• 제42권6호
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• pp.671-678
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• 2004

Statement of problem. Reducing treatment time in implant dentistry is a matter of main concern. There are so many factors affecting the success rate of immediate or early loaded implant for the initial bone response. The especially microscopic properties of implant surfaces playa major role in the osseous healing of dental implant. Purpose. The aims of this study were to perform a histologic and histomorphometric comparison of the healing characteristics anodically roughened surface, HA coated surface and RBM surface implant, and to compare of ISQ values measured by $Osstell^{TM}$ for resonance frequency analysis in dogs mandible during 2 weeks. Material and method. Bone blocks from 2 dogs were caught after covered healing for 0 day(2 h); Group I, 1 week; Group II and 2 weeks; Group III. One longitudinal section was obtained for each implant and stained with hematoxylin and eosin. Histomorphometric analysis was done with Kappa Imagebase system to calculate bone-to-implant contact and bone volumes inside the threads. ISQ values were measured in every time of surgery schedule. Conclusion. The experiment revealed that: 1. The percentages of bone-to-implant contact on the fixture in each group were not significantly different(P > 0.05). 2. The percentages of bone area inside the threads on the fixture in each group were not significantly different(P > 0.05). 3. The ISQ level showed clinical stability of each fixture during 2 weeks(all ISQ level ${\geq}71$ ).

• 대한치과보철학회지
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• 제42권5호
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• pp.544-555
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• 2004

Statement of problem: Shade selection has traditionally been accomplished by visual examination, which is particularly relevant to the shade selection of anterior teeth, but the subjective nature of visual analysis can lead to errors in shade matching. Recently shade selection systems have been developed to provide a more objective and scientific approach to understanding and clarifying shade selection. Purpose : The purpose of this study was analysis of various shade analyzing equipment with the goal of providing a more objective shade selection. Materials and method: Visual shade matching system selection(Vita Lumin Vacuum shade guide, Vitapan 3D Master shade guide) and mechanical shade matching method($ShadeEye^{(R)}$-EX Chroma Meter, $Shadescan^{TM}$ System) used for this study. The shade guide tap specimens for 10 extracted maxillary anterior teeth were produced by selecting shades using each shade matching system. The accuracy of the selection of shades for the teeth and fabricated specimens were evaluated by analyzing the calculated shade difference(${\Delta}E^*$), using a spectrophotometer and calculating the output of value $L^*,\;a^*,\;b^*$. Results and conclusion: The results show that the average ${\{Delta}E^*$ value (difference of shade) of the shade tap specimens to the actual specimen decreased in the following order: Vita Lumin Vacuum Shade Guide(VL), $ShadeEye^{(R)}$-EX Chroma Meter(SE) Vitapan 3D Master Shade guide(V3), and $Shadescan^{TM}$ System(55) : and that there are significant statistical differences between the VL and SS (p<0.05). In the analysis of the ${\Delta}E^*$ (difference of shade) value,40% of the VL group was found to be less than 3.3 (limit value of shade tap specimens clinically acceptable), 60% in the V3 group, 50% in the SE group, and 80% in the SS group.

• 정보관리학회지
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• 제29권1호
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• pp.331-349
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• 2012

구조적 초록은 학술 논문의 주제를 표현하는 역할을 하여 학술 논문을 처리하는데 중요한 요소로 인식되어왔다. 이 연구에서는 구조적 초록을 구성하는 세부 필드의 속성을 4개로 분석하고 초록의 구조를 활용하여 문서 클러스터링에 적용할 수 있는 가능성을 고찰고자 하였다. 구조적 초록의 필드 속성을 문서 클러스터링에 적용한 결과 클러스터링 기법간의 편차가 있었으나 연구 목적이 제공하는 정보량에 비해 주제성이 커서 클러스터링 성능에 가장 큰 영향을 미치고 있는 것으로 나타났다. 또한 분석 결과 특정 필드에 특화되어 출현하는 필드 종속적인 단어가 발생하는 것으로 나타나 필드 종속적인 단어를 배제하고 집단내 평균연결 기법을 적용하였을 때는 클러스터링의 성능이 개선되는 것으로 분석되었다.

• 대한치과보철학회지
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• 제43권5호
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• pp.633-649
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• 2005

Statement of problem: In spite of the progress in techniques and materials in complete denture prosthodontics, patients still complain of discomfort after the insertion of complete dentures. For the last several decades many prosthodontists tried to find factors influencing patient complete denture satisfaction, however the reported results became a controversy. Purpose: The purpose of the present study was to verify the factors influencing patient satisfaction with complete dentures using multiple regression analysis. Materials and methods: 33 patients who visited the department of prosthodontics, dental hospital of Yonsei University, 4 to 6 weeks after the complete denture delivery, were asked to complete the questionnaires on complete denture satisfaction, social variables and psychological variables. The Prosthodontists who treated the patients with complete dentures were also asked to complete the questionnaires on evaluation of patients' oral condition and technical quality of dentures. The factors influencing patients' satisfaction with their complete dentures were analyzed using multiple regression analysis. Results: Among the patients' sociodemographic variables. the variables of relationship with children, economic status, housing condition, other people's opinions of dentures and gender were the influential factors on patients' satisfaction with complete dentures. Patients showing the symptoms of depression, one of the psychological variables, were dissatisfied with their complete dentures. In spite of the good oral condition, patients were dissatisfied with complete dentures, where-as the technical quality of dentures did not influence patients' complete denture satisfaction. Conclusion : According to the results above, patients' sociodemographic and psychological variables rather than clinical variables including oral condition and technical quality of dentures were the influential factors on complete denture satisfaction. The results of this study may not only enable prosthodontists to predict the success and failure of complete denture treatment, but also help both prosthodontists and patients be informed of the essentials of increasing satisfaction with complete dentures.

• 대한간호학회지
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• 제49권6호
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• pp.701-712
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• 2019

Purpose: Despite the high drinking rates and the complexity of drinking behaviors in adolescents, insufficient attention has been paid to their drinking patterns. Therefore, we aimed to identify patterns of adolescent drinking behaviors and factors predicting the distinct subgroups of adolescent drinking behaviors. Methods: We analyzed nationally representative secondary data obtained in 2017. Our final sample included 24,417 Korean adolescents who had consumed at least one glass of alcohol in their lifetime. To investigate patterns of drinking behaviors, we conducted a latent class analysis using nine alcohol-related characteristics, including alcohol consumption levels, solitary drinking, timing of drinking initiation, and negative consequences of drinking. Furthermore, we investigated differences in demographics, mental health status, and characteristics of substance use across the latent classes identified in our study. To do so, we used the PROC LCA with COVARIATES statement in the SAS software. Results: We identified three latent classes of drinking behaviors: current non-drinkers (CND), binge drinkers (BD), and problem drinkers (PD). Compared to the CND class, both BD and PD classes were strongly associated with higher academic year, lower academic performance, higher levels of stress, suicidal ideation, lifetime conventional or electronic cigarette use, and lifetime use of other drugs. Conclusion: Health professionals should develop and implement intervention strategies targeting individual subgroups of drinking behaviors to obtain better outcomes. In particular, health professionals should consider different characteristics across subgroups of adolescent drinking behaviors when developing the interventions, such as poor mental health status and other substance use among binge and problem drinkers.

• 대한치과보철학회지
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• 제43권2호
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• pp.218-231
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• 2005

Statement of problem. In the partially edentulous patients, removable partial dentures have been working as a important treatment modality. Clasps, a kind of direct retainers, received some amount of stresses during the insertion and removal of partial denture on the abutment tooth. Purpose. The study is to investigate stresses of the different clasps. Material and methods. In order to investigate the degree of stresses, maxillary partial edentulism (Kennedy Class II modification I) was assumed and removable partial dentures were designed on it with three kinds of metallic materials; cobalt-chromium alloy, type IV gold alloy and commercially pure (c.p.) titanium. Aker's clasp was applied on the left second molar. RPA (mesial rest-proximal plate-Aker's) clasp was on the left first premolar and wrought wire clasp was on the right first premolar. Three dimensional, non-linear, dynamic finite element analysis method was run to solve this process. Results. 1. Cobalt-chromium alloy had the highest von Mises stress value and c.p. titanium had the lowest one irrespective of the types of clasps. 2. In the Aker's clasps, stress on the retentive tips was shown shortly after the appearance of stresses of the middle and minor connector areas. These time lag was much shorter in the RPA clasps than in the Aker's clasp. 3. In general. retentive tips of wrought wire clasps had much less amount of stress than other clasps. Conclusion. The amount of stress was the highest in the RPA clasp and the lowest in the wrought wire clasp, in general.

• 대한치과보철학회지
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• 제41권2호
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• pp.169-181
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• 2003

Statement of problem : The survival rate of wide diameter implants was lower than of 3.75-mm implants in some clinical researches. Purpose : The purpose of this study was to investigate the influence of implant diameter on the osseointegration of implants in the rabbit femoral condyle and tibial metaphyses by means of removal torque measurements and histomorphometric analysis. Material and Method : Ten adult New Zealand White rabbits were used in this study Two 3.75-mm diameter implants were inserted through one cortical layer in the tibial metaphyses and one 3.75-mm diameter implant was inserted in the femoral condyle. 5.0-mm diameter implants were inserted in the other leg in the same manner. A total of 60 implants (3.75-mm diameter implants:30 : 5.0-mm diameter implants:30) were installed. After a healing time of 4 and 12 weeks, the peak removal torque values required to shear off the implants were recorded. From the removal torque values (Ncm) obtained, the mean shear stress ($N/mm^2$) was calculated. And the percentage of direct bone-to-implant contact and the percentage of bone area inside the thread were measured by Kappa Image Base-metreo. The Student's t-test was undertaken for statistical analysis (p<0.05). Results : The removal torque value of 5.0-mm diameter implants was higher than of 3.75-mm diameter implants (p<0.05). The difference of shear stress value between 3.75-mm and 5.0-mm diameter implants was not statistically significant (p>0.05). The percentage direct bone-to-implant contact had no statistical difference between two groups (p>0.05). The percentage of bone area inside the thread had no statistical difference between two groups (p>0.05). Conclusion It is concluded that the quality f osseointegration is not influenced by increasing implant diameter.

• The Journal of Advanced Prosthodontics
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• 제1권1호
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• pp.1-5
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• 2009

STATEMENT OF PROBLEM. Poor wettability of denture relining materials may lead to retention problems and patient discomfort. PURPOSE. Purpose of this study is to compare and evaluate wettability of nine denture relining materials using contact angle measurements under air and water storage over time. MATERIAL AND METHODS. Nine denture relining materials were investigated in this study. Two heat-curing polymethyl-methacrylate(PMMA) denture base materials: Vertex RS, Lang, one self-curing polyethyl-methacrylate(PEMA) chairside reline resin: Rebase II, six silicone relining materials: Mucopren soft, Mucosoft, $Mollosil^{{R}}$ plus, Sofreliner Touch, GC $Reline^{TM}$ Ultrasoft, Silagum automix comfort were used in this experiment. Contact angles were measured using high-resolution drop shape analysis system(DSA 10-MK2, KRUESS, Germany) under three conditions(in air after setting, 1 hour water storage, and 24 hours water storage). Nine materials were classified into three groups according to material composition(Group 1: PMMA, Group 2: PEMA, Group 3: Silicone). Mean values of contact angles were compared using independent samples t-test and one-way ANOVA, followed by a Scheffe's post hoc analysis($\alpha$=0.01). RESULTS. Contact angles of materials tested after air and water storage increased in the following order: Group 1(PMMA), Group 2(PEMA), Group 3(Silicone). Heat-cured acrylic denture base resins had more wettability than silicone relining materials. Lang had the highest wettability after 24 hours of water storage. Silicone relining materials had lower wettability due to their hydrophobicity. Wettability of all denture relining materials, except Rebase II and $Mollosil^{{R}}$ plus, increased after 24 hours of water storage. CONCLUSIONS. Conventional heat-cured resin showed the highest wettability, therefore, it can be suggested that heat-cured acrylic resin is material of choice for denture relining materials.