• 한국재료학회지
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• 제15권9호
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• pp.560-565
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• 2005

The objective of this paper is to decide optimal of the slot angle to minimize stress concentration in rotating disc of diamond saw. The fracture phenomena of the slot are discussed by the theoretical and experimental approaches and then some recommendation are presented to prevent the fracture. The focus of this investigation is to evaluation the effect of the slot on stress distribution using optimum design technique and finite element method(FEM) analysis. Stress concentration of the slot with respect to the various parameter of the slot such position, size, number, rotation speed. From the experimental results, when the slot angle of diamond saw is located $8^{\circ}\~12^{\circ}$ from rotating direction, the maximum equivalent stress reduces.

• Restorative Dentistry and Endodontics
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• 제14권1호
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• pp.205-210
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• 1989

The purpose of this study was to observe the minim pins of Link plus (which has buttress thread and shoulder stop design) inserted into dentin and the dentin surrounding pin. The gingival walls of class II cavity were prepared with high speed handpiece in molar teeth not elapsed time after teeth were extracted, and pinhole of 2mm in depth was positioned about 1 mm to the dentinoenamel junction and minim pin was inserted with wrench. After initial examination of the specimens, the specimens were sectioned longitudinally and horizontally to the pins with carborundum disc and low speed diamond saw (Isomet Buehler Ltd) All specimens were coated Au of 250-300${\AA}$ in thickness with Ion Sputter JFC 100 and observed under Scanning Electron Microscope (JSM-35) The following results were obtained. 1. The shoulder stop was seated on the enterance of pinhole in gingival wall, and there were the irregular space between the pin and dentin at the enterance to the pin hole and flakes of dentin lifting from the dentin floor. 2. In case of section to pin horizontally or longitudinally, the dentin debris were observed in gap between pin and dentin, and small cracks were often seen in the dentin surrounding minim pins.

• 대한치과보철학회지
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• 제29권1호
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• pp.91-109
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• 1991

The purpose of this study were to comfirm the effects of the thickness and kinds of porcelain, etchants, illumination time, elapsed time for the measurement, and chemical cure component to the bond strength of porcelain laminate and composite resin cement, and to compare the effects between the light cured resin and the dual cured resins. The etched porcelain surface, the sectioned surface crossing porcelain and resin after bonding, and the debonded surfaces were observed by the SEM. One product of laminate porcelain powder, one light cured resin and two dual cured resins were selected. Each resin cements are lightened through the thin porcelain disc which was cut from cylindrical porcelain specimen by the diamond saw, and by the light through the porcelain disc they were bonded. Changes of thickness and kinds of porcelain, etchants, illumination time, and the elapsed time for the measurement were considered as variables for the bond strength. And the bond strength of porcelain and dual cured resins under the conditions of autopolymerization or the removal of chemical cure component were measured and compared. Bond strength were measured by shear stress. The etched surface, the cross-sectioned surface, and the debonded surface of porcelain or resin were observed by SEM. On the summary of this study, the following conclusions can be stated; 1. Bond strength of light cured resin was decreased inversely by the thickened porcelain laminate and showed the lowest value to the masking dentin porcelain among 4 kinds of porcelain powder. 2. Bond strength of autopolymerization of dual cured resin without illumination in dark chamber were from 75% to 98% to the data of dual cured resin with illumination. 3. Bond strength of dual cured resin used without chemical cured components were same to them of light cured resin. 4. Cross-sectioned surface treated by silane did not show the gap between the porcelain and resin. 5. Illumination over 80 seconds did not make the significant increase of bond strength on all kinds of resin.

• 대한치과보철학회지
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• 제26권1호
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• pp.153-169
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• 1988

There is a little scientific documentation reporting the stress, distribution to the edentulous mandible by different concepts of occlusal scheme. So, this study was to investigate the hypothesis that the magnitude and distribution of the occlusal stresses, transmitted through a mandibular complete denture base to the edentulous mandible, would be influenced by the lingualized occlusion. This investigation was performed to analyze the stresses induced in a three-dimensional photoelastic edentulous mandible, when a load is applied to the denture arranged into lingualized occlusion in centric relation, lateral and protrusive functional position. The mounted denture on a Dentatus Type ARO articulator was loaded in a pure vertical direction with 15kgs on the center of articulator in each case and the stresses were frozen into epoxy edentulous model at $127^{\circ}C$ in the stress freezing furnace. The stress-frozen epoxy models were sliced with diamond disc saw into 4mm thick. The slices were examined with a circular polariscope. The results were as follows: 1. In centric relation, the stresses were low at anteriors, and gradually increase to the premolar, molar area and highest at the first molar and gradually decrease from the second molar and lowest at the retromolar pad region. The lingual side showed higher stresses than labiobuccal side. 2. In lateral functional position, the working side showed higher stresses than the balancing side. In working side, the lingual side showed higher stresses than the buccal side and in balancing side, the buccal side showed higher stresses than the lingual side. 3. In protrusive position, stress distribution was symmetrical on the posteriors and the stresses were concentrated at the labial side of the anteriors.

• Applied Microscopy
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• 제31권4호
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• pp.307-314
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• 2001

12주령 랫드의 비골의 골절을 유발한 후 골절치유에 미치는 홍화씨 분말의 영향을 알아보고자 실험을 실시한 결과 다음과 같은 결과를 얻었다. 비골의 골절은 골절유발 후 5주에 성숙된 신생골 조직으로 충만되어 조직형태학적으로 완전한 유합이 이루어지는데, 홍화씨 분말을 투여한 결과 골절유발 후 4주에 성숙된 신생골 조직으로 골절단이 충만되어 완전한 유합을 이룬 후 5주에서는 골수강도 개통되는 등 대조군과 비교하여 유합시기를 기준으로 1.5주 정도의 빠른 골절의 치유가 이루어졌다. 이상의 결과는 홍화씨 분말에 골절의 치유를 촉진시키는 성분이 포함되어 있을 가능성을 시사한다고 사료된다.