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IPS Empress 도재관의 파절강도 : 상악제1소구치에서 교합면 두께와 축면 경사도에 따른 영향
동진근,오상천,김상돈,Dong, Jin-Keun,Oh, Sang-Chun,Kim, Sang-Don 대한치과보철학회 1999 대한치과보철학회지 Vol.37 No.1
The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the occlusal depth (1.5mm, 2.0mm, 2.5mm) and axial inclination ($4^{\circ},\;8^{\circ},\;12^{\circ}$) of the upper first premolar. After 10 metal dies were made fir each group, the IPS Empress ceramic crowns were fabricated and each crown was cemented on each metal die with resin cement. The cemented crowns mounted on the testing jig were inclined 30 degrees and a universal testing machine was used to measure the fracture strength. The results were : 1. The fracture strength of the ceramic crown with 2.5mm depth and $12^{\circ}$ inclination was the highest (630N). Crowns of 1.5mm depth and $4^{\circ}$ inclination had the lowest strength(378N). There were no significant differences of the fracture strength by axial inclination in same occlusal depth group. 2. The fracture mode of the crowns was similar. Most of fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth.
주입선 및 열처리에 따른 IPS Empress 도재의 미세구조에 관한 연구
동진근,오상천,Dong, Jin-Keun,Oh, Sang-Chun 대한치과보철학회 1998 대한치과보철학회지 Vol.36 No.5
This study was undertaken to clarify the microstructure of the different IPS Empress ingots by etching and to observe the change of leucite crystal structure according to subsequent heat treatment and the crystal distribution according to sprue types(${\phi}2.8mm$, single sprue; ${\phi}1.8mm$, double sprue) by scanning electron microscopy. IPS Empress T1, O1 ingots used for staining technique, and Dentin(A2) ingots used for layering technique were selected for this study. To observe the microstructures of these ingots before pressing, the specimens were prepared in splinters($3{\times}3{\times}3mm$) taken from the original ingots. And to estimate crystal distribution and microstructural change by sprue type and subsequent heat treatment. the specimens($3{\times}3{\times}3mm$) were heat-pressed through the two types of sprues with different diameters and numbers, and all specimens were fired according to the recommended firing schedule. The observed surface was ground with waterproof papers($#800{\sim}#1800$) on the grind polisher and was cleaned ultrasonically. All specimen were etched with 0.5% hydrofluoric acid. After etching, the surface was treated by ion sputter coating for SEM observation at an accelerating voltage of 20kV. In all specimens, the central area of ground surface was observed because there was less difference in microstructure between the peripheral area and the central area. The results were as follows ; 1. In the microstructure according to the ingot type, there was a wide difference between the staining (T1,O1) and layering(Dentin A2) ingots, but there was not a considerable difference between the T1 ingot and the O1 ingot for staining technique. 2. In all specimens, the crystal dispersion of IPS Empress ceramic using double sprue was significantly more scattered than that of IPS Empress ceramic using single sprue. The degree of scattering was strongest in the Dentin(A2) specimen and weakest in the O1 ingot. 3. In the microstructural change according to the subsequent heat treatment, all of ingots had some microcracks in the inside of the leucite crystal and the glass matrix after pressing. The inner splinters of the leucite crystal became smaller, and more microcracks occurred in the glass matrix due to increasing heat treatment times. 4. The size of leucite crystals varied from $1{\mu}m\;to\;5{\mu}m$. The mean size of mature crystals was about $5{\mu}m$. The form of the crystal was similar to a circle when it was smaller and similar to an ellipse when it was larger.
MMPI Clinical Scale와 미소평점과의 상관성에 관한 연구
동진근,오상천,김현성,주태훈 원광대학교 치의학연구소 1996 圓光齒醫學 Vol.6 No.1
This study was designed to investigate the correlation between MMPI (The Minnesota Multiphasic Personality Inventory) clinical scale scores and smile scores. The MMPI test was administered to 60 university students(male: 30, female: 30) who have no teeth missing, no experience of orthodontic or prosthodontic treatment and good dentition. Then, portraits were taken in a full smile. Esthetic smile scores were estimated by 10 appraisers who were dentists. These scores were analyzed statistically using the SAS program. The following results were obtained. 1. As MMPI clinical scales of Femininity is increased and Social Introversion is decreased, results showed high aesthetic level of smile. 2. For females, personality factors had greater influence on smile aesthetics, whereas male smile aesthetics were less influenced by personality factors.
Coping design에 따른 도재전장관의 파절강도에 관한연구
정완모,동진근,진태호 원광대학교 치의학연구소 1992 圓光齒醫學 Vol.2 No.1
The purpose of this study was to evaluate the effect of the metal coping design on the fracture resistance of ceramometal crown. The Ni-Cr alloy (Supranium,Krupp Co.,Germany) and Vaccum-fired porcelain powder (Vita VMK 68, Vita Co., Germany) were used in this study. The measurement of fracture resistance of ceramometal crown was done with Instron Universial Testing Machine (Instron Co., model no.4201). The obtained results were as follows 1. The fracture resistance measured at the buccal cusp tip was the highest value in the group that those position of ceramometal junction was 2㎜ superior to the lingual finishing margin (100.25㎏) and the fracture resistance revealed on order of the group that those position was 2 mm lingual to the central groove (70.21㎏), the group that those position was 2㎜ buccal to the central groove (51.64㎏). 2. The fracture resistance measured at the central groove was higher value in the group that those position was 2㎜ lingual to the central groove than in the group that those position was 2㎜ superior to lingual finishing margin (132.48㎏). 3. In all cases, the fracture resistance at the central groove was higher than that at the buccal cusp tip.