• 대한치과기공학회지
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• 제30권2호
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• pp.17-22
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• 2008

The purpose of this study was to observe the thermal expansion of the inlay waxes at temperature. Inlay pattern wax shows not only a high coefficient of expansion but also a tendency to warp or distort when allowed to stand unrestrained. The thermal expansion of inlay waxes was tested according to the treatment conditions for 10 minutes at $40^{\circ}C$ The thermal expansion of inlay waxes at various temperatures was measured with an electro dial gauge. The results were as fellows: 1. It is shown that the rate of thermal expansion of wax A is 0.2%, wax B is 0.29%, wax C is 0.38%, and wax D is 0.22% at $40^{\circ}C$ 2. It is shown that the coefficient of thermal expansion of wax A is $106{\times}10^{-6}/^{\circ}C$, wax B is $152{\times}10^{-6}/^{\circ}C$, wax C is $199{\times}10^{-6}/^{\circ}C$, and wax D is $116{\times}10^{-6}/^{\circ}C$ at $40^{\circ}C$ 3. The thermal expansion of the inlay waxes at $40^{\circ}C$ was shown to increase in the order of wax C, B, D, A.

• 대한치과기공학회지
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• 제28권2호
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• pp.367-373
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• 2006

This study was performed to observe the flow change of the inlay waxes at various temperatures. The flow of inlay waxes was tested according to the treatment conditions, for 10 minutes at 40$^{\circ}C$, 41$^{\circ}C$, 42$^{\circ}C$, 43$^{\circ}C$, 44$^{\circ}C$, and 45$^{\circ}C$ The flow of inlay waxes at various temperatures was measured with an electro dial gauge. The results were as fellows: 1. The flow change of the inlay waxes at various temperatures was shown to increase in the order of wax A, B, D, C. 2. Wax A was close to ADA specification with 3% flow at 40$^{\circ}C$ and 71% flow at 45$^{\circ}C$, but wax B and D did not reach up to ADA specification with 40% flow at 45$^{\circ}C$. 3. Wax C came up with 3% flow at 40$^{\circ}C$ and 7% flow at 45$^{\circ}C$, and it revealed a very low flow change at 5$^{\circ}C$.

• 대한치과기공학회지
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• 제2권1호
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• pp.17-19
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• 1980

This study was aimed at obtaining a desirable wax pattern for inlay. The method used was to analyze, mix, and heat several kinds of waxes, comparing the temperatures of their components. The result was Type C wax. In type C the amount of paraffin was generally contained(60$\sim$70%) was reduced to 45% and there was mixed 10%-15% of carnauba, which was intended for the wax not to soften readily at low temperatures. The type C has some advantages for general use: handy preparation, high safety, and economy. The inlay waxes commonly used contracted if the temperature fell from 38 to 28, but the contraction of type C was observed to be 0.2%$\sim$0.4% in proportion to the 10 fall. This was more characteristic in mixing.

• 대한치과의사협회지
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• 제22권4호통권179호
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• pp.269-269
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• 1984

• Restorative Dentistry and Endodontics
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• 제16권2호
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• pp.155-164
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• 1991

The purpose of this study was to evaluate the effects of bleaching agent through the dentinal tubules of cervical area in the intracoronal bleaching of pulpless teeth on cutured fibroblast cells. Extracted human incisors were enlarged to # 40 K-file and obturated with gutta-perella and AH 26 sealer. The gutta-percha was removed to 2mm below the cementoenamel junction of the root The teeth were divided into 3 experimental and control groups. Experimental groups; Experimental group 1: Temporary inlay wax filld with 30% $H_2O_2$ in pulp cavity. Experimental group 2: Temporary inlay wax filld with 30% $H_2O_2$ in pulp cavity after placement of ZOE cement to cementoenamel junction. Experimental group 3: Temporary inlay wax filld with 30% $H_2O_2$ in pulp cavity after application of Copalite to cementoenamel junction. Control group: Temporary inlay wax filled without 30% $H_2O_2$ in pulp cavity under the same condition at each experimental group. Each tooth was immersed in well of multidish cultured fibroblast cell for 48 hours. The cellular multiplication and cell viability were calculated at the interval of 1, 3, 5. 7 hours and the morphological changes in well were observed and their photographs were taken with inverted microscope. The obtained results were as follows : CD The cellurar multiplicaton and cell viability decreased in all experimental groups at 1 hour after experiment and the morphology of fibroblast cell was changed from star shape to round (2) The cell viability was lowered to 34 % in experemental group 1, 44 % in experimental group 2, and 38 % in experemental group 3 at 3 hours after experiment (3) The cell multiplication was decreased to 54% in experemental group 1. 47% in experimental group 2, and 40% in experemental group 3 at 7 hours after experiment. (4) The decrease of cell number and morphological changes of fibroblast cell were remarkable in experimental group 1, group 3 and 2 in order. These results suggest that the fibroblast cells receive severe damage by 30% $H_2O_2$ solution leaked through the dentinal tubules and the dentinal tubules are able to be obturated better by ZOE cement than by Copalite.

• 대한치과보철학회지
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• 제16권1호
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• pp.17-21
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• 1978

The object of this study was to measure of the distortion of various dental waxes under condition simulating clinical usage. Eleven commercial product (table) including the inlay and baseplate waxes were tested, and compared in the study. Test specimens were prepared $5{\times}5{\times}65mm$. split brass mold. Placed this rod wax specimens and the brass wax distortion test mold into the water bath and tested the distortion values for waxes at $35^{\circ}C,\;40^{\cric}C,\;45^{\circ}C\;and\;50^{\circ}C$. Measured the distortion as the difference between the final (Df) and original (Do) distance between the ends of the specimen. Recorded Df, Do and Df-Do (Distortion) to the nearest 0.5mm. A minimum of five specimens were tested for each material. The following conclusions may be drawn from this study. 1) It can be seen that, a significant wax distortion was obtained with the temperature of forming the pattern, and the length of time and the temperature at which it was stored. 2) It was found that, when the storage time was increased, the wax distortion was correspondingly increased. At the sametime, the higher the storage time was employed, the distortion was obviously much greater. 3) It can be observed that the higher the temperature at which the wax was manipulated, the less was the resulting distortion upon storage.

• 대한치과기공학회지
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• 제42권1호
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• pp.9-16
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• 2020

Purpose: The purpose of this study was to compare the marginal and internal fit of lithium disilicate ceramic inlay produced by heat pressing that inlay pattern made by subtractive manufacturing and additive manufacturing method. Methods: A mandibular lower first molar that mesial occlusal cavity (MO cavity) die was prepared. After fabricating an epoxy resin model using a silicone impression material, epoxy resin die was scanned with a dental model scanner to design an MO cavity inlay. The designed STL pile was used to fabricate wax patterns and resin patterns, and then lithium disilicate ceramic inlays were fabricated using hot-press method. For the measurement of the marginal and internal gap of the lithium disilicate, silicone replica method was applied, and gap was measured through an optical microscope (x 80). Data were tested for significant differences using the Mann-Whitney Utest. Results: The marginal fit was 103.56±9.92㎛ in the MIL-IN group and 81.57±9.33㎛ in the SLA-IN group, with a significant difference found between the two groups (p<0.05). The internal fit was 120.99±17.52㎛ in the MIL-IN group and 99.18±6.65㎛ in the SLA-IN group, with a significant difference found between the two groups (p<0.05). Conclusion: It is clinically more appropriate to apply the additive manufacturing than subtractive manufacturing method in producing lithium disilicate inlay using CAD/CAM system.

• The Journal of Advanced Prosthodontics
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• 제10권4호
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• pp.321-327
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• 2018

PURPOSE. The purpose of this study was to compare the cutting method and the lamination method to investigate whether the CAD data of the proposed inlay shape are machined correctly. MATERIALS AND METHODS. The Mesial-Occlusal shape of the inlay was modeled by changing the stereolithography (STL). Each group used SLS (metal powder) or SLA (photocurable resin) in the additive method, and wax or zirconia in the subtractive method (n=10 per group, total n=40). Three-dimensional (3D) analysis program (Geomagic Control X inspection software; 3D systems) was used for the alignment and analysis. The root mean square (RMS) in the 2D plane state was measured within $50{\mu}m$ radius of eight comparison measuring points (CMP). Differences were analyzed using one-way analysis of variance and post-hoc Tukey's test were used (${\alpha}=.05$). RESULTS. There was a significant difference in RMS only in SLA and SLS of 2D section (P<.05). In CMP mean, CMP 4 ($-5.3{\pm}46.7{\mu}m$) had a value closest to 0, while CMP 6 ($20.1{\pm}42.4{\mu}m$) and CMP 1 ($-89.2{\pm}61.4{\mu}m$) had the greatest positive value and the greatest negative value, respectively. CONCLUSION. Since the errors obtained from the study do not exceed the clinically acceptable values, the lamination method and the cutting method can be used clinically.

• 대한치과교정학회지
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• 제31권4호
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• pp.467-477
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• 2001

이 연구의 목적은 호선으로 유도되는 치아이동을 실험실에서 실험하는 동안 브라켓과 선재의 운동 마찰저항에 대한 브라켓 수, 브라켓 폭경, 선재 크기가 미치는 영향을 관찰하기 위한 것이다. 상악 제 1, 2소구치, 제 1대구치와 유사한 크기의 레진 치아를 사용하였으며, 치주인대와 탄성계수가 비슷한 폴리 에테르 인상재를 사용하였다. 스테인레스 스틸 트윈 에지와이즈 브라켓으로 좁은 폭경 (2.4 mm), 중간 폭경 (3.0 mm), 넓은 폭경 (4.3 mm)을 사용하였으며, 강선으로는 0.016, 0.018, $0.016\;{\times}\;0.022,\;0.019\;{\times}\;0.025$인치의 굵기를 사용하였고, 결찰은 합성고무링을 이용하고, 제1소구치에 부착된 좁은 폭경 브라켓 1개, 제 1, 2소구치에 부착된 2개의 중간 폭경 브라켓 및 제 1, 2소구치와 제 1대구치에 부착된 3개의 중간 폭경 브라켓과 각 강선 사이의 운동 마찰저항력을 계측하여 다음의 결론을 얻었다. 1. 좁은 폭경, 중간 폭경, 넓은 폭경 세 종류의 브라켓 모두에서 교정용 선재의 단면 크기가 증가할수록 마찰저항력도 증가하였다. 2. 0.016, 0.018인치 원형 강선은 브라켓 폭경이 증가하면 운동마찰저항력은 감소하며, $0.016\;{\times}\;0.022,\;0.019\;{\times}\;0.025$인치 각형 강선은 브라켓 폭경이 증가하면 운동마찰저항력이 증가하는 경향이 있었고0.016인치 원형 강선과 폭경이 다른 브라켓과의 운동마찰저항력 사이에는 통계적으로 유의차가 없었다. 3. 중간 폭경 브라켓의 수가 증가할수록 마찰저항력은 크게 나타났으며, 그 증가율은 브라켓의 수에 비례하였으나 정수배로 증가하지는 않았고 강선의 굵기에 따라 차이가 있었다.