• The Journal of Korean Academy of Prosthodontics
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• v.43 no.5
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• pp.599-610
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• 2005

Purpose: The success of the bonding between electroformed gold and ceramic is dependent on the surface treatment of the pure gold coping. The purpose of this study was to evaluate the bonding strength between the electroformed gold and ceramic with varying surface treatment. Materials and methods: A total of 32 disks,8 were using conventional ceramometal alloy, 24 were using electroforming technique as recommended by manufacturer, were prepared. 24 electroformed disks were divided 3 groups according to surface treatment, i.e. 50 microns aluminium oxide sandblasting(GES-Sand), gold bonder treatment(GES-Bond) and $Rocatec^{TM}$ system(GES-Rocatec). For control group of conventional alloy 50 microns aluminium oxide treatment was done(V-Supragold). Energy dispersive x-ray analysis and scanning electron microscope image were observed. Using universal testing machine, shear bond strength and bonding failure mode at metal-porcelain interface were measured. Results and Conclusion: The following conclusions were drawn: 1. In the energy dispersive x-ray analysis, the Au was main component in electroformed gold(99.9wt%). After surface treatment, a little amount of $Al_2O_3(2.4wt%)$ were found in GES-Sand, and $SiO_2(4wt%)$ in GES-Bond. In GES-Rocatec, however, a large amount of $SiO_2(17.4wt%)$ were found. 2. In the scanning electron microscopy, similar pattern of surface irregu larities were observed in V-Supragold and GES-Sand. In GES-Bond, surface irregularities were increased and globular ceramic particles were observed. In GES-Rocatec, a large amount of silica particles attached to metal surface with increased surface irregularities were observed. 3. The mean shear bond strength values(MPa) in order were $22.9{\pm}3.7(V-Supragold),\;22.1{\pm}3.8(GES-Bond),\;20.1{\pm}2.8(GES-Rocatec)\;and\;13.0{\pm}1.4(GES-Sand)$. There was no significant difference between V-Supragold, GES-Bond, and GES-Rocatec. (P>0.05) 4. Most bonding failures modes were adhesive type in GES-Sand. However, in V-Supragold, GES-Bond and GES-Rocatec, cohesive and combination failures were commonly observed. From the result, with proper surface treatment method electroformed gold may have enough strength compare to conventional ceramometal alloy.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.4
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• pp.301-309
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• 2015

Purpose: The aim of this study was to evaluate the clinical performance of screw- and cement-retained implant prosthesis (SCP) design in terms of retained preload of abutment screws and cement washout. Materials and methods: Patients with the partial posterior edentulous areas comprised the study group. Implants were placed, and SCPs were delivered after 3 to 6 months healing. Follow-up examinations were performed. The implant survival rate and the prosthetic success rate were evaluated. The retained preload ratio of abutment screws and the prosthetic decementation ratio were measured. Results: Twenty one SCPs (forty three implants)in twenty patients were followed up to 64 months. All of the implants survived during the follow-up period (mean follow-up: 34 months). The prosthetic success rate was 100 % considering no abutment, screw, porcelain or metal frame fractures, as well as no screw loosening. The retained preload ratio of SCPs at the end of follow-up period was 97.61% (${\pm}16.29$) and the decementation ratio was 9.5 %. Conclusion: Within the limitations of this clinical study, SCP design showed favorable short-term clinical performances in respect of screw loosening and cement washout.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.5
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• pp.463-476
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• 2001

Since the treatment of edentulous patients with osseointegrated implant was first introduced more than 30 years ago, implant therapy has become one of the most important dental treatment modalities today. Based on the previous experience and knowledge, $Br{\aa}nemark\;Novum^{(R)}$ protocol was introduced with the concept of simplifying surgical and prosthetic technique and reducing healing time recently. This protocol recommends the installation of three 5mm wide diameter futures in anterior mandible and the prefabricated titanium bars for superstructure fabrication. This study was designed to analyze the stress distribution at fixture and superstructure area according to changes of fixture number, diameter and superstructure materials. Four 3-dimensional finite element models were fabricated. Model 1 - 5 standard fixtures (13mm long and 3.75mm in diameter) & superstructure consisted of type IV gold alloy and resin Model 2- 3 wide diameter fixtures (13mm long and 5.0mm in diameter) & superstructure consisted of type IV gold alloy and resin Model 3-3 wide diameter fixtures (13mm long and 5.0mm in diameter) & superstructure consisted of titanium and resin Model 4-3 wide diameter fixtures (13mm long and 5.0mm in diameter) & superstructure consisted of titanium and porcelain A 150N occlusal force was applied on the 1st molar of each model in 3 directions - vertical($90^{\circ}$), horizontal($0^{\circ}$) and oblique($120^{\circ}$). After analyzing the stresses and displacements, following results were obtained. 1. There were no significant difference in stress distribution among experimental models. 2. Model 2, 3, 4 showed less amount of compressive stress than that of model 1. However, tensile stress was similar. 3. Veneer material with a high modulus of elasticity demonstrated less stress accumulation in the superstructure. Within the limites of this study, $Br{\aa}nemark\;Novum^{(R)}$ protocol demonstrated comparable biomechanical properties to conventional protocol.

• Journal of the Korean Institute of Landscape Architecture
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• v.18 no.1
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• pp.1-8
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• 1990

Forty different apartment houses were subjected to assess the status of indoor - landscaping plants found at each apartment house in Seoul for the year of 1986 and 7989. 1. Comparing with those of 1986, 46% increase in total indoor plant species and 68% increase in the number of them were observed. The most abundant sort found in 1786 was oriental orchid, African violet, Scindapsus, cacti, and Clivia, and in 1989, first with oriental orchid, cacti, Chlorophytum, Clivia and Dracaena, in that order. 2. Foliage ornamental plants were mast popularly found in both years of 1986 and 1989 when considered for horticultural classification of plants. 3. Average plant height ranged between 15 to 30 cm in the year of i986, whereas 31 to 80 cm in 1987, indicaling that the size of plants has greatly increased. 4. Kind of planters or containers was most frequently shown to be made of plastic material in both years, and the porcelain ones have significantly been increased to use recently. 5. Most indoor plants placed at the rooms were on the floor in those years, yet the use of planting shelves became particularly manifesting in the year of 1989. 6. Fittonia and cacti were the most frequently used plant materials for installing terrariums at apartment rooms In the year of 1986, whereas Adiantum and Maranta were so in 1989, indicating that the growers choose much adaptable species in apartment environments. Most of the plants grown to landscaping the indoors was apartment verandas in those years. 8. Average number of indoor plants possessed at each apartment houses surveyed for the year of 1986 was 16 different ones, whereas 27 each In 1789, shoving a noteworthy increase in the number. 9. There have been apparent increase and improvement inhabitant's indoor - plant interest in the years to pass and probably to come.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.3
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• pp.319-332
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• 2021

With the rapid development of aesthetic ceramic materials and resin adhesives, the transition from metal ceramic crown to all-ceramic restoration is being actively carried out. When making porcelain restorations, the advantages can be maximized only when appropriate forms and techniques are used. Recently, an esthetic partial-coverage restoration method with supra-gingival margins was introduced by applying a minimally invasive tooth removal method that preserves enamel as much as possible and enhances adhesion efficiency. Through this, various advantages such as minimization of tooth structure removal and ease of excess cement removal can be obtained. In addition, since this manufacturing method does not require cord packing, it is possible to save time for impression taking and reduce patient discomfort. Furthermore, the margins can be clearly obtained without the intervention of gingival fluid or blood, making it possible to manufacture more accurate restorations. In the following cases of patients with partial tooth defects, esthetic ceramic partial-coverage restorations with supra-gingival margin was applied using minimally invasive tooth preparation method according to the concept of adhesive dentistry. Therefore, unnecessary tooth abutment preparation was prevented and residual tooth structure could be preserved as much as possible. After delivery of the ceramic partial-coverage restorations, favorable outcome was obtained.

• Korean Journal of Heritage: History & Science
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• v.53 no.1
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• pp.150-167
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• 2020

The purpose of this paper is to share the status and introduce a scientific analysis of the GeumguJagi (gilt-silver overlay porcelain, 金釦瓷器) excavated from Seongneung (石陵). This analysis aimed to highlight the GeumguJagi excavated from the Royal Tombs of Goryeo with a clear lower year (1237) and to aid research into the GeumguJagi. In 2001, the National Institute of Cultural Heritage excavated and investigated Seongneung in Heejong (熙宗). Various artifacts such as celadon, gold, bronze, and iron products were collected from the chambers inside of the tomb. There were a total of 160 celadon items including bowls, dishes, glasses, and saucers. Of those, there were 58 celadon items (including fragments) with metal frames on the openings. These consisted of bowls, plates, lids, and saucers. Until recently, in various exhibitions and papers, only one GeumguJagi was known to have been excavated from Seongneung, which was a . However, the survey identified a number of further GeumguJagis. It had been understood from inherited and excavated products that the materials used for ornaments were restricted to high-quality celadon. However, this study confirmed that the excavation of Seongneung demonstrated the use of various other materials for different models and qualities of GeumguJagis. It can be said that it is characteristic that various models and quality are confirmed together through the excavation of Seongneung. A scientific analysis was carried out that selected 12 of 58 products excavated from Seongneung. Results showed that the main component used for Geumgu ornaments was tin (Sn), and trace amounts of copper (Cu) and lead (Pb) were also commonly identified. When analyzing the material used to affix the metal fittings, this was found to be glue (膠) made from animal skins, muscle, and bones. This pattern matches that of the GeumguJagi excavated from Paju Hyeeumwonji, and the reason for this could be assumed on the basis of the contents of the 『Cheongonggaemul (天工開物)』 written by Song Ongsung (宋應星) during the Ming Dynasty. At that time, metals such as tin and copper would have been difficult to obtain. 『Xuānhwafengshi Gaolitujing (宣和奉使高麗圖經)』 shows that the use of metal was limited to certain classes; thus, the use of the GeumguJagi seems to have been centered around the royal family.

• Restorative Dentistry and Endodontics
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• v.32 no.1
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• pp.19-27
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• 2007

The purpose of this study is to develope new dental color-space system. Twelve kinds of dental composites and one kind of dental porcelain were used in this study. Disk samples (15 mm in diameter, 4 mm in thickness) of used materials were made and sample's CIE $L^*a^*b^*$ value was measured by Spectrocolorimeter (MiniScan XE plus, Model 4000S, diffuse/$8^{\circ}$ viewing mode, 14.3 mm Port diameters, Hunter Lab USA) The range of measured color distribution was analyzed. All the data were applied in the form of T### which is expression unit in CNU Cons Dental Color Chart. The value of $L^*$ lies between 80.40 and 52.70. The value of $a^*$ are between 10.60 and 3.60 and $b^*$ are between 28.40 and 2.21. The average value of $L^*$ is 67.40, and median value is 67.30. The value of $a^*$ are 2.89 and 2.91 respectively. And for the $b^*$, 14.30 and 13.90 were obtained. The data were converted to T### that is the unit count system in CNU-Cons Dental Color Chart. The value of $L^*$ is converted in the first digit of the numbering system. Each unit is 2.0 measured values. The second digit is the value of $a^*$ and is converted new number by 1.0 measured value. For the third digit $b^*$ is replaced and it is 2.0 measured unit apart. T555 was set to the value of $L^*$ ranging from 66.0 to 68.0, value of $a^*$ ranging from 3 to 4 and $b^*$ value ranging from 14 to 16.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.239-245
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• 2016

Purpose: The purpose of this study was to identify clinical complications in removable partial denture (RPD) with implant-supported surveyed prostheses, and to analyze the factors associated with the complications such as location of the implant, splinting adjacent prostheses, the type of retentive clasps, Kennedy classification, and opposing dentition. Materials and Methods: A retrospective clinical study was carried out for 11 patients (7 male, 4 female), mean age of 67.5, who received RPD with Implant-supported surveyed prostheses between 2000 and 2016. The mechanical complications of 11 RPDs and 37 supporting implant prostheses and the state of natural teeth and peripheral soft tissue were examined. Then the factors associated with the complications were analyzed. Results: The average of 3.4 implant-supported prostheses were used for each RPD. Complications found during the follow-up period of an average of 42.1 months were in order of dislodgement of temporary cement-retained prostheses, opposing tooth fracture/mobility, screw fracture/loosening, clasp loosening, veneer porcelain fracture, marginal bone resorption and mobility of implant, artificial tooth fracture. Complications occurred more frequently in anterior region compared to posterior region, non-splinted prostheses compared to splinted prostheses, surveyed prostheses applied by wrought wire clasp compared to other clasps, and natural dentition compared to other removable prostheses as opposing dentition. There were no significant differences in complications according to the Kennedy classification. Conclusion: All implant-assisted RPD functioned successfully throughout the follow-up. However, further clinical studies are necessary because the clinical evidences are still not enough to guarantee the satisfactory prognosis of implant-assisted RPD for long-term result.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.2
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• pp.71-79
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• 2017

Purpose: Ni-Cr alloy does not contain Beryllium, causing the metal compound to form oxides in the furnace but by using Titanium as a chemical catalyst the forming of the oxides can be controlled, and by controlling the impurities formed on the metal surface, the possibility of the Ni-Cr alloy bond strength being increased can be analysed. Materials and Methods: Titanium was used as a chemical catalyst in the porcelain for the oxidation of beryllium-free metal (Ni-Cr) alloy. The T1 group, which does not use Titanium power as a chemical catalyst is a reference model for comparison. The T2 group and T3 group used 10 g and 20 g of Titanium power, respectively. They are fabricated to observe the shear bond strength and surface properties. There was no significance when One-way ANOVA analysis/Tukey Honestly Significant Difference Test was conducted for statistical analysis among groups (P > 0.05). Results: Results of measuring the three-point flexural bond strength of the Ni-Cr alloy and thickness of the oxide film. Experiment T3 using 20 g Titanium chemical catalyst: $39.22{\pm}3.41MPa$ and $6.66{\mu}m$, having the highest bond strength and thinness of oxide film. Experiment T2 using 10 g Titanium chemical catalyst: $34.65{\pm}1.39MPa$ and $13.22{\mu}m$. Experiment T1 using no Titanium chemical catalyst: $32.37{\pm}1.91MPa$ and $22.22{\mu}m$. Conclusion: The T2 and T3 experiments using Titanium chemical catalyst showed higher bond strength for the Ni-Cr alloy and lower thickness of oxide film than experiment T1, and the titanium catalyst being able to increase bond strength was observed.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.73-79
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• 2011

Purpose: The aim of this study was to evaluate the effect of repeated firings on the color of zirconia restoration with different shading method. Materials and methods: Three different types of zirconia frameworks (adding metallic pigments to the initial zirconia powder before sintering (Group NM), dipping the milled frameworks in dissolved coloring agents (Group KI), or application of liner material to the sintered white frameworks (Group KW) were used to support A3 shade dentin porcelain. Repeated firings (3, 5, or 7) were performed, color differences among ceramic specimens were measured using a colorimeter. Repeated measurements analysis of variance (ANOVA) was used to analyze the data for significant difference. The Tukey Honestly Significant Different (HSD) test was used to perform multiple comparisons (${\alpha}$ = .05). Results: 1. $L^*a^*b^*$ values of the ceramic systems were affected by the number of firings (1, 3, 5 or 7 firings) (P < .001) and shading methods (P < .001). 2. As the number of firings increased, the $L^*$ (for all groups) and $a^*$ value (for KW and NM groups) decreased and the $b^*$ value(for all groups) increased. 3. The mean color differences caused by repeated firings were perceptible (${\Delta}E$ > 1) for group KW and KI fired after 3 times, except for group NM fired after 7 times. 4. In order of decreasing ${\Delta}E$ value fired after 7 times, the values were group KI(${\Delta}E$ = 2.26) > group KW (${\Delta}E$ = 1.47) > group NM (${\Delta}E$ = 1.08) (P < .001). Conclusion: Repeated firings influenced the color of the zirconium-oxide all-ceramic specimens with different shading methods.