• The Journal of Korean Academy of Prosthodontics
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• v.47 no.3
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• pp.312-319
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• 2009

Statement of problem: Delamination of veneering porcelain from underlying ceramic substructures has been reported for zirconia-ceramic restorations. Colored zirconia cores for esthetics have been reported that their bond strength with veneered porcelain is weaker compared to white zirconia cores. Purpose: This study aimed to investigate the shear bond strength by manufacturing the veneering porcelain on the colored zirconia core, using the layering technique and heat-pressing technique, and to evaluate the clinical stability by comparing the result of this with that of conventional metal ceramic system. Material and methods: A Metal ceramic (MC) system was tested as a control group. The tested systems were Katana zirconia with CZR (ZB) and Katana Zirconia with NobelRondo Press (ZP). Thirty specimens, 10 for each system and control, were fabricated. Specimen disks, 3 mm high and 12 mm diameter, were fabricated with the lost-wax technique (MC) and the CAD-CAM (ZB and ZP). MC and ZB specimens were prepared using opaque and dentin veneering ceramics, veneered, 3 mm high and 2.8 mm in diameter, over the cores. ZP specimens were prepared using heat pressing ingots, 3 mm high and 2.8mm in diameter. The shear bond strength test was performed in a Shear bond test machine. Load was applied at a cross-head speed of 0.50 mm/min until failure. Mean shear bond strengths (MPa) were analyzed with the One-way ANOVA. After the shear bond test, fracture surfaces were examined by SEM. Results: The mean shear bond strengths (SD) in MPa were MC control 29.14 (2.26); ZB 29.48 (2.30); and ZP 29.51 (2.32). The shear bond strengths of the tested systems were not significantly different (P > .05). All groups presented cohesive and adhesive failures, and showed predominance of cohesive failures in ceramic veneers. Conclusion: 1. The shear bond strengths of the tested groups were not significantly different from the control group (P >.05). 2. There was no significant different between the layering technique and the heat pressing technique in the veneering methods on the colored zirconia core. 3. All groups presented cohesive and adhesive failures, and showed predominance of cohesive failures in ceramic veneers.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.2
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• pp.163-173
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• 2013

When the mandible performs opening movement, the condyle-disk complex conducts sliding movement along the articular eminence. Thus, anatomic configuration of articular eminence is very important to normal movement of TMJ. The purpose of this study was to measure the posterior slope of the articular eminence and evaluate the effect of a pathologic bone change in the condylar head on the stiffness of articular eminence, and compare the differences of the articular eminence slope by gender and age using dental cone-beam CT. As using i-CAT Cone-Beam Computed Tomography, the CT images of 204 TMJs of 102 patients(43 men and 59 women, mean age: 37.7 years) who were diagnosed at Wonkwang University Sanbon Dental Hospital were evaluated. All images were converted into a TMJ analysis mode to observe the continuous sagittal section images and coronal section images of the joints. To observe and assess bone changes in the condyle, three dentists measured the stiffness of the articular eminence on the same images, and when two of the three dentists agreed on their reading, these results were adopted and recorded. The articular eminence slope, considering the condylar anatomic configuration, was measured in three regions, namely, lateral part, central part, and medial part of the condyle. In the cases of a normal condyle(NCBC) and a condyle(CBC) with bone change, the articular eminence slopes were $57.0^{\circ}$(NCBC) and $51.8^{\circ}$(CBC) at the medial part, $57.9^{\circ}$(NCBC) and $52.4^{\circ}$(CBC) at the central part, and $55.1^{\circ}$(NCBC) and $49.5^{\circ}$(CBC) at the lateral part of the condyle. And the articular eminence slope of the condyle with bone change demonstrated less steepness than that of normal condyle (p<0.05). The articular eminence slope showed mediolaterally that it was the steepest at the central, followed by at the medial, and at the lateral (p<0.05). There were no significant differences by the gender and the age (p.0.05).

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.7
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• pp.953-958
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• 2005

This study was conducted to investigate the effect of beverage (beverage HC and beverage PG) using herbs on antimicrobial activity, proliferation of hepatic cancer cell (Hep3B) lines and sarcoma 180 (S-180) and antiallergy, respectively. Beverage PG showed higher antimicrobial activity than beverage HC against Staphylococcus aureus and Pseudomonas aeruginosa. Beverage HC and PG showed the tumor suppressive effect in mice injected with S-180 cells. The growth-inhibitoy ratio against tumor cells were $66\%\;for\;10\%$ beverage HC, $61\%\;for\;10\%$ beverage PG. In an anti-cancer test using Hep3B cells, beverage PG showed higher anti-proliferating effect than beverage HC. Beverage PG showed growth-inhibitory effect of $69.2\%\;at\;100\%$ beverage PG. Beverage PG inhibited histamine release from rat peritoneal mast cells (RPMC) activated by compound 48/80. In conclusion, these results suggest that beverage using herbs have an antimicrobial activity, anti-proliferating effect against Hep3B cell and S-180 tumor and will be beneficial in treatment of allergic reaction.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.1
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• pp.55-60
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• 2010

Purpose: The shrinkage of dental resin cement may cause several clinical problems such as distortion that may jeopardize the accurate fit to the prepared tooth and internal stress within the restorations. It is important to know the polymerization shrinkage-strain of dental resin cement to reduce clinical complications. The purpose of this study was to investigate the polymerization shrinkage-strain kinetics of six commercially available dental resin cements. Material and methods: Three self-cure resin cements (Fujicem, Superbond, M-bond) and three dual-cure resin cements (Maxcem, Panavia-F, Variolink II) were investigated. Time dependent polymerization shrinkage-strain kinetics of the materials were measured by the Bonded-disk method as a function of time at $23^{\circ}C$, with values particularly noted at 1, 5, 10, 30, 60, 120 min after mixing. Five recordings were taken for each materials. The data were analyzed with one-way ANOVA and Scheffe post hoc test at the significance level of 0.05. Results: Polymerization shrinkage-strain values were 3.72%, 4.19%, 4.13%, 2.44%, 7.57%, 2.90% for Fujicem, Maxcem, M bond, Panavia F, Superbond, Variolink II, respectively at 120 minutes after the start of mixing. Panavia F exhibited maximum polymerization shrinkage-strain values, but Superbond showed minimum polymerization shrinkage-strain values among the investigated materials (P < .05). There was no significant differences of shrinkage-strain value between Maxcem and M bond at 120 minutes after the start of mixing (P > .05). Most shrinkage of the resin cement materials investigated occurred in the first 30 minutes after the start of mixing. Conclusion: The onset of polymerization shrinkage of self-cure resin cements was slower than that of dual-cure resin cements after mixing, but the net shrinkage strain values of self-cure resin cements was higher than that of dual-cure resin cements at 120 minutes after mixing. Most shrinkage of the dental resin cements occurred in the first 30 minutes after mixing.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.3
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• pp.207-216
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• 2020

Purpose: To compare the polishing characteristics and their influence on Candida albicans adhesion to the recently introduced polyetherketoneketone (PEKK) and the conventional polymethylmethacrylate (PMMA) denture resin material. Materials and methods: Specimens from PEKK (Group E) and PMMA (Group M) were made in dimensions of 8 mm in diameter and 2 mm in thickness. The specimens were further divided into sub-groups according to the extent of polishing (ER, MR: rough; EP, MP: polished, N = 12 each). The specimens were polished using polishing machine and SiC foil. ER and MR group specimens were polished with 600 grit SiC foil only. EP and MP groups were further polished with 800, 1,000, 1,200 grit SiC foils sequentially. To measure the surface roughness values (Sa) of specimens, atomic force microscope (AFM) was used and scanning electron microscope (SEM) observation under 1,000, and 20,000 magnifications was performed to investigate surface topography. The polished specimens were soaked in C. albicans suspension for 2 hours with shaking to promote adhesion. The attached C. albicans were detached from the surface with 10 times of pipetting. The suspension of detached C. albicans was performed by serial dilution to 10³ times, and the diluted suspensions were inoculated on Sabouraud dextrose agar plates using spread plate method. After incubating the plate for 48 hours, colony forming unit (CFU)/plate of C. albicans was counted. Statistical analysis was performed using one-way ANOVA and Tukey HSD test to confirm significant difference between the groups (α=.05). Results: Average Sa value was significantly higher in MR group compared to other groups (P<.05), meaning that additional polishing steps reduced surface roughness effectively only in the PMMA specimens. There was no significant difference in Sa values between MP and EP groups. In SEM images, PEKK specimens showed numerous spikes of abraded material protruding from the surface and this phenomenon was more significant in EP group. The mean CFU/plate value was the highest in EP group and this was significant when it was compared to MP group (P<.05) which was the lowest. Conclusion: Polishing PEKK using serial SiC abrasive foil may result in higher adhesion of C. albicans. In clinic, this should be considered carefully.

• Restorative Dentistry and Endodontics
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• v.36 no.4
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• pp.324-335
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• 2011

Objectives: This study investigated the effects of the color components of light-cured composite resin before and after polymerization on degree of conversion (DC) and biaxial flexural strength (FS). Materials and Methods: Four enamel shades (A1, A2, A3, A4) and two dentin shades (A2O, A3O) of Premisa (Kerr Co.) and Denfil (Vericom Co.) were evaluated on their CIE $L^*,\;a^*,\;b^*$ color components using the spectrophotometer before curing, after curing and at 7 day. The DC of same specimens were measured with Near-infrared spectrometer (Nexus, Thermo Nicolet Co.) at 2 hr after cure and at 7 day. Finally, the FS was obtained after all the other measurements were completed at 7 day. The correlations between each color component and DC and FS were evaluated. Results: The light-curing of composite resin resulted in color changes of Premisa in red-blue direction and Denfil in green-blue direction. The DC and FS were affected by product, time and shade (3-way ANOVA, p < 0.05) and product and shade (2-way ANOVA, p < 0.05), respectively. Premisa only showed a significant correlation between the DC and CIE $a^*$ component - before and after polymerization (Pearson product moment correlation, p < 0.05). The FS of Premisa showed significant negative correlations with CIE $a^*$ and CIE $b^*$ components. Conclusions: The DC and FS of the light-curing composite resin were affected by the color components of the material before and after polymerization.

• Korean Journal of Dental Materials
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• v.45 no.4
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• pp.257-274
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• 2018

The purpose of this study was to evaluate the effect of acid-treatment conditions on the surface properties of the RBM (Resorbable Blast Media) treated titanium. Disk typed cp-titanium specimens were prepared and RBM treatments was performed with calcium phosphate ceramic powder. Acid solution was mixed using HCl, $H_2SO_4$ and deionized water with 4 different volume fraction. The RBM treated titanium was acid treated with different acid solutions at 3 different temperatures and for 3 different periods. After acid-treatments, samples were cleaned with 1 % Solujet solution for 30 min and deionized water for 30 min using ultrasonic cleanser, then dried in the electrical oven ($37^{\circ}C$). Weight of samples before and after acid-treatment were measured using electric balance. Surface roughness was estimated using a confocal laser scanning microscopy, crystal phase in the surface of sample was analyzed using X-ray diffractometer. Surface morphology and components were evaluated using Scanning Electron Microscope (SEM) with Energy Dispersive X-ray spectroscopy (EDX) and X-ray Photoemission Spectroscopy (XPS). Values of the weight changes and surface roughness were statistically analyzed using Tukey-multiple comparison test (p=0.05). Weight change after acid treatments were significantly increased with increasing the concentration of $H_2SO_4$ and temperature of acid-solution. Acid-treatment conditions (concentration of $H_2SO_4$, temperature and time) did not produce consistent effects on the surface roughness, it showed the scattered results. From XRD analysis, formation of titanium hydrides in the titanium surface were observed in all specimens treated with acid-solutions. From XPS analysis, thin titanium oxide layer in the acid-treated specimens could be evaluated. Acid solution with $90^{\circ}C$ showed the strong effect on the titanium surface, it should be treated with caution to avoid the over-etching process.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.3
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• pp.31-38
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• 2019

This study quantified, through a direct harvesting method, storage and annual uptake of carbon from open-grown trees for three landscape tree species frequently planted in the southern region of Korea, and developed quantitative models to easily estimate the carbon reduction by tree growth for each species. The tree species for the study included Camellia japonica, Lagerstroemia indica, and Quercus myrsinaefolia, for which no information on carbon storage and uptake was available. Ten tree individuals for each species (a total of 30 individuals) were sampled considering various stem diameter sizes at given intervals. The study measured biomass for each part of the sample trees to quantify the total carbon storage per tree. Annual carbon uptake per tree was computed by analyzing the radial growth rates of the stem samples at breast height or ground level. Quantitative models were developed using stem diameter as an independent variable to easily calculate storage and annual uptake of carbon per tree for study species. All the quantitative models showed high fitness with $r^2$ values of 0.94-0.98. The storage and annual uptake of carbon from a Q. myrsinaefolia tree with dbh of 10 cm were 24.0 kg and 4.5 kg/yr, respectively. A C. japonica tree and L. indica tree with dg of 10 cm stored 11.2 kg and 8.1 kg of carbon and annually sequestered 2.6 kg and 1.2 kg, respectively. The above-mentioned carbon storage equaled the amount of carbon emitted from the gasoline consumption of about 42 L for Q. myrsinaefolia, 20 L for C. japonica, and 14 L for L. indica. A tree with the diameter size of 10 cm annually offset carbon emissions from gasoline use of approximately 8 L for Q. myrsinaefolia, 5 L for C. japonica, and 2 L for L. indica. The study pioneers in quantifying biomass and carbon reduction for the landscape tree species in the southern region despite difficulties in direct cutting and root digging of the planted trees.

• MISULJARYO - National Museum of Korea Art Journal
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• v.96
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• pp.209-223
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• 2019

The Iron Seated Buddha sculpture in the National Museum of Korea had long sat unregistered in storage at the museum. However, a new accession number "bon9976" has recently been assigned to it. This sculpture was excavated from the neighborhood of Heungnyongsa Temple in Baekun-ri, Yidong-myeon, Pocheon-gun, Gyeonggi-do Province together with another Iron Seated Buddha sculpture(bon9975) called "Iron Buddha from Pocheon." A comparison and examination of Gelatin Dry Plate and official documents from the Joseon Government-General Museum during the Japanese occupation period have revealed that these two Iron Buddha sculptures were transferred to the Museum of the Government-General of Korea on December 17, 1925. The Iron Seated Buddha sculpture(bon9976) has a height of 105 centimeters, width at the shoulders of 57 centimeters, and width at the knee of 77 centimeters. The Buddha is wearing a robe with rippling drapery folds and the right shoulder exposed. He is seated in the position called gilsangjwa(the seat of good fortune) in which the left foot is placed over the right thigh. The features of the Buddha's oval face are prominently sculpted. The voluminous cheeks, eye sockets in a large oval shape, slanted eyes, short nose, and plump lips can also be found in other ninth-century Iron Seated Buddha sculptures at Silsangsa Temple in Namwon, Jeollanam-do Province, Hancheonsa Temple in Yecheon, Gyeongsangbuk-do Province, and Samhwasa Temple in Donghae-si, Gangwon-do Province. Moreover, its crossed legs, robe exposing the right shoulder, and rippling drapery folds suggest that this sculpture might have been modeled after the main Buddha sculpture of the Seokguram Grotto from the eighth century. The identity of this Iron Seated Buddha can be determined using the Gelatin Dry Plate(M442-2, M442-7). In them, the Buddha has its right palm facing upwards and holds a medicine jar on its left palm. Until now, the Iron Seated Bhaiṣajyagura(Medicine) Buddha(bon1970) excavated from Wonju has been considered the sole example of an iron Medicine Buddha sculpture. However, this newly registered Iron Seated Buddha turns out to be a Medicine Buddha holding a medicine jar. Furthermore, it serves as valuable material since traces of gilding and lacquering clearly remain on its surface. This Iron Seated Buddha sculpture (bon9976) is presumed to have been produced around the ninth century under the influence of Esoteric Buddhism by the Monk Doseon(827~898), a disciple of the Monk Hyecheol, to protect the temple and help the country overcome geographical shortcomings. According to the records stored at Naewonsa Temple(later Heungnyongsa Temple), Doseon selected three significant sites, including Baegunsan Mountain, built "protector" temples, created the Bhaisajyagura Buddha triad, and enshrined them at the temples. Moreover, the inscription on the stele on the restoration of Seonamsa Temple states that Doseon constructed temples and produced iron Buddha sculptures to help the country surmount certain geographical shortcomings. Heungnyongsa Temple is located in Dopyeong-ri, Yidong-myeon, Pocheon-si, Gyeonggi-do Province. This region appears to have been related to rituals directed to the Medicine Buddha since Yaksa Temple(literally, "the temple of medicine") was built here during the Goryeo Dynasty, and the Yaksa Temple site with its three-story stone pagoda and Yaksadong Valley still exist in Dopyeong-ri.