• Journal of Korea Foundry Society
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• v.20 no.3
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• pp.208-215
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• 2000

The mechanical properties and corrosion resistance of Ti alloys for medical implants have been investigated. Ti, Ti-15Sn-4Nb and Ti-15Sn-4Nb-2Zr alloys were melted in arc furnace and the corrosion resistance of Ti alloys was evaluated by anodic polarization test. The microstructure and mechanical properties of Ti alloys were analysed by optical microscope, hardness and tensile tester. The tensile strength of the pure-Ti improved by addition of Sn and Nb and Ti-15Sn-4Nb alloy showed better Rockwell hardness compared with pure Ti. However, there was no significant difference in corrosion resistance between thoseTi-alloys made of Pure-Ti and Ti-15Sn-4Nb alloy. The passive films on the Ti-15Sn-4Nb alloy in air atmosphere consisted of $TiO_2$, SnO and NbO as demonstrated by X-ray photoelectron spectroscopy(XPS)

• Korean Journal of Materials Research
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• v.19 no.8
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• pp.412-416
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• 2009

In this study, 3 mol% yttria-tetragonal zirconia polycrystal (3Y-TZP) nanoparticles were synthesized by the glycothermal method under various reaction temperatures and times. The co-precipitated precursor of 3Y-TZP was prepared by adding $NH_4OH$ to starting solutions, and then the mixtures were placed in an autoclave reactor. Tetragonal yttria-doped zirconia nanoparticles were afforded through a glycothermal reaction at a temperature as low as $220^{\circ}C$, using co-precipitated gels of $ZrCl_4$ and $YCl_3{\cdot}6H_2O$ as precursors and 1,4-butanediol as the solvent. The synthesized 3Y-TZP particles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy. The 3Y-TZP particles have a stable tetragonal phase only at glycothermal temperatures above $200^{\circ}C$. To investigate phase transition, the 3Y-TZP particles were heat treated from 400 to $1400^{\circ}C$ for 2 h. Raman analysis indicated that, after heat treatment, the tetragonal phase of the 3Y-TZP particles remained stable. The results of this study, therefore, suggest that 3Y-TZP powders can be prepared by the glycothermal method.

• Journal of the Korea Convergence Society
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• v.9 no.9
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• pp.123-133
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• 2018

This study aims to evaluate the overall health of the disabled and oral health behavior to determine its relevance to DMFT index. Based on the National Health Nutrition Survey. The survey was conducted on disabled adults over 19years old age in 2013 the first of 6th phase. The data analysis included a general characteristics, disability factors, social economy factors, health factors, oral health behavior factors were cross-analyzed on a composite sample. The general linear model of the combined sample was analyzed to determine the factors affecting the DMFT index of the disabled. The analysis shows that the DMFT index is higher for men than for women, the higher age, the lower level of education, the worse condition of whole body(EQ-5D), the difficulty of Stomatognathic system, the uncomfortable of chewing and the worse oral health conditions subjectively. Therefore, the study objectively identified the overall oral health condition of the adult disabled in Korea, Through this study, a measure should be made to development of comprehensive oral health education program to promote oral health of disabled people and policy measures should be prepared for prevention and care of oral health of disabled people.

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.39-45
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• 2008

Titanium and its alloys are widely used as dental implants materials because of their excellent mechanical properties. However, the alumina and zirconia ceramics are preferred to use as the substitute of Ti implants because there is a problems in esthetics and biocompatibility in Ti implant. The the glass infiltrated alumina ceramics are studied to increase the toughness and biocompatibility. The 45S5 and soda-lime glass powder was mixed with ethanol at ratio of 1:1 and brushed on the surface of alumina. Then it was heat treated in the electric furnace at $1400^{\circ}C$ from 30 min. to 5 hours. The glass powder was controlled from 200 to $350{\mu}m$ using ball milling. After heat treatment, the glass infiltrated specimen was tested in universal testing machine to measure the bending strength. The surface microstructure of each specimen was observed with SEM. The biocompatibility of 45S5 and soda-lime glass coated alumina was investigated using PBS at $36.5^{\circ}C$ incubator. The specimen was immersed in PBS for 3, 5, 7, 10 days. After that, the surface morphology was investigated with SEM. As the results of experiment, the 45S5 bioglass infiltrated alumina show the increase of bending strength according to the increasing of heat treatment time from 30 min. to 5 hours at $1400^{\circ}C$ Finally the 1370N bending strength of alumina increased to 1958N at 5 hours heat treatment, which shows 1.4 times higher. In contrast to this, the soda lime glass infiltrated alumina ceramics shows the convex curve according to heat treatment time. Thus it shows maximum bending strength of 1820N at 1 hour heat treatment of $1400^{\circ}C$ It gives 1.3 times higher. However, the bending strength of soda lime glass infiltrated alumina is decreasing with increasing heat treatment time after 1 hour. The precipitation on the surface of 45S5 glass infiltrated alumina was revealed as a sodium phosphate ($Na_{6}P_{6}O_{24}6H_{2}O$) and the amount of precipitation is increasing with increasing of immersion time in PBS. In contrast to this, there is no precipitation are observed on the surface of soda lime glass infiltrated alumina. This implies that 45S5 glass infiltrated alumina brings more biocompatible when it is implanted in human body.

• Journal of Digital Convergence
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• v.17 no.10
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• pp.373-379
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• 2019

Polymethyl methacrylate (PMMA), a self-polymerizing resin for removable orthodontic devices, has been used as a dental orthodontic device for many years because of its advantages such as color stability, volume stability, and tissue compatibility. However, such a removable orthodontic device has a disadvantage that the longer the use in the oral cavity due to the low strength of the PMMA fracture of the orthodontic device resin in use. In this study, zinc nanoparticles (ZNP) were mixed with orthodontic PMMA to introduce strength effect. Rectangular samples ($1.4{\times}3.0{\times}19.0mm$) of orthodontic PMMA (0, 0.5, 1.0, 2.0 and 4.0%) containing ZNP were prepared. The finished specimen was tested for three-point bending strength at a speed of 1 mm / min, and the Vickers hardness was measured three times using a hardness tester. The surface roughness was measured with a surface roughness. As a result, the 3-point bending strength did not change significantly (p>0.05). Surface energy increased significantly. As a result, we successfully synthesized ZNP in this study and prepared the dispersed resin specimen for calibration. It will be possible to develop high-density dental orthodontic resins.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.1
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• pp.34-41
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• 2022

Recently, digital technology and computer-aided design/computer-aided manufacturing (CAD/CAM) environment have changed the clinician treatment method in the fabrication of dentures. The denture manufacturing method with CAD/CAM technology simplifies the treatment and laboratory process to reduce the occurrence of errors and provides clinical efficiency and convenience. In this case, complete dentures were fabricated using stereolithography (SLA)-based 3D printing in patient with mandibular deviation. Recording base were produced in a digital model obtained with an intraoral scanner, and after recording a jaw relation in the occlusal rim, a definitive impression was obtained with polyvinyl siloxane impression material. In addition, facial scan data with occlusal rim was obtained so that it can be used as a reference in determination of the occlusal plane and in arrangement of artificial teeth during laboratory work. Artificial teeth were arranged through a CAD program, and a gingival festooning was performed. The definitive dentures were printed by SLA-based 3D printer using a Food and Drug Administration (FDA)-approved liquid photocurable resin. The denture showed adequate retention, support and stability, and results were satisfied functionally and aesthetically.

• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.9-14
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• 2018

The purpose of this study was to evaluate the relationship between past smoking period and tooth loss in Korean elderly based on the data the Sixth Korea National Health and Nutrition Examination Survey (2013-2015). The study subjects were 4,037 elderly people (1,737 men and 2,300 women) over 65 years old. The statistical analyses were conducted by applying complex sample analysis technique using SPSS/WIN 22.0(${\alpha}=0.05$). The average number of tooth loss in Korean elderly was 11.14. The analysis result of the relationship of the tooth loss according to the past smoking period, the risk of tooth loss was more than twice higher in over 30 years past smoking period group than in under 10 years past smoking period group. In conclusion, the long term past smoking were associated with tooth loss in Korean elderly. Therefore, it seems to need a continuous oral health care through non-smoking policy and education.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.3
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• pp.168-175
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• 2023

Long-term use of inappropriate prosthesis often results in habitual closure or irregular mandibular movements. In that case, guide to the stable centric position is difficult. Therefore, by using a treatment denture, the muscles and TMJ should be stabilized and the jaw relation should be acquired with the treatment position. Compared to the conventional method, digital technology in fabrication complete denture has the advantage of reproducing a stable tooth arrangement in cases of difficult tooth alignment, minimizing laboratory errors and reducing denture fabrication time. Therefore, in this case, the final denture was fabricated by digitally reproducing the stable treatment position, vertical dimension, and lip support with a treatment denture, and satisfactory results were obtained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.176-182
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• 2018

One of the most important factor of esthetic prosthesis is the color of the teeth. Zirconia is produced in the process of design, milling, coloring, drying, and sintering. The effect of the drying degree of zirconia colorant on the color tone is examined. For the experiment, a total of 45 zirconia specimens(15 for each) were fabricated by using cad/cam system. The zirconia specimens(L block(LAZOR), Z block(Zircos-E block posterior), A block(AlphaZ)) were then subjected to zirconia sintering in accordance with the manufacturer's instructions, using a chemical coloring agent to Non-drying(0sec), intermediate (10sec), and completely dried (10min) temperature holding times. The color tone was measured using a spectrophotometer. The results were analyzed with a One-way analysis of variance and the Tukey post-hoc test (${\alpha}=.05$) The $L^*$ values of L, A specimens, $a^*$ values of A specimens, and $b^*$ values of Z specimens were not statistically different according to the degree of drying (p>0.05), While the $L^*$ value of Z specimen, $a^*$ value of L, Z specimen, $b^*$ values of L, A specimens were statistically different according to the degree of drying(p <0.05). In conclusion, the drying of zirconia colourants improves zirconia brightness and increases the optical properties of the enamel.

• Journal of Technologic Dentistry
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• v.35 no.2
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• pp.145-155
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• 2013

Purpose: The recent proliferation of the aging population, oral health care is closely related to the mental health of the elderly is very important being recognized. Provide basic data for improving the quality of life for the elderly, to determine whether the oral health of the elderly whether oral self-perception of health and any related wish. Methods: Surveys to May 20 from April 15, 2011, subjects were elderly and living in Daejeon and Chungnam 277 people were examined. All the statistics using SPSS 18.0 for the determination of statistical significance, and the significance level was 0.05. Results: 1. Recognized, the most common oral health, self-aware bad the state (46.2%) there was no significant difference in the general characteristics according to self-Oral health status, remaining natural dimensions or the intra-oral prosthetic, there was no significant difference. More teeth, residual phase, in accordance with intra-oral prosthetic mandibular Not all dentures, partial dentures, full dentures net self-perception of oral health status better recognized. 2. According to the type of partial dentures, oral health status self-phase, mixed mandibular removable, fixed, fixed, removable partial dentures in order to recognize that good oral health, self-aware state, showed between them, there was no significant difference. 3. Of variable dimension that has nothing to do with the remaining natural maxillary and mandibular prosthetic maxillary prosthetic mandibular partial dentures, age income, a positive correlation was negatively correlated. The case of the mandible, the mandibular prosthetic mandibular partial denture, maxillary prosthetic, the amount of income were correlated. 4. Intra-oral Prosthetics correlation variables in the maxillary, mandibular prosthesis, the positive correlation between income, age was negatively correlated, if the income of the mandible. Maxillary partial denture has nothing to do with the variable portion of the mandibular denture, age was a negative correlation was found. Conclusion: Satisfaction and how now it is important simply to live as long, but you need to pay attention to the quality of life, sometimes with an aging population and the increase of soybean To buy the loss of teeth causes the typical health problems of the elderly. Elderly people of any relevant oral health and the oral cavity by the state to determine whether to provide the basic data for oral health education was more residual value, intra-oral prosthetics there is no more self-aware, the oral health status is good to recognize that appeared. Strengthen the oral health education to improve the quality of life of the elderly, and is thought to be necessary to increase the number of residual.