• 대한치과보철학회지
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• 제45권4호
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• pp.522-533
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• 2007

Statement of problem: Despite of the recent development of the titanium casting system methods, the casting defects such as imperfect casting and internal porosity were frequently observed. Purpose: The purposes of this study were to compare and measure the castability, microhardness, and surface reaction between Grade 2 pure titanium and Ti-6Al-4V by casting these alloys from the different sprue design conditions. Material and methods: Depending on the sprue designs and titanium alloys, 42 ready-made wax patterns were used. By analyzing the remodeling of the cast, internal porosity, microhardness, and titanium surface layer of SEM, there were several results we observed. Results: 1. The measured castability of titanium were categorized in the ascending order: individual sprue group, runner bar group, and single group. This data are based on the statistically signigicant differences. 2. The castability of titanium has not showed the statistically significant differences among the alloys. However, CP-Ti groups were superior to Ti-6Al-4V groups by showing the noticeable castability. 3. The surface layers of the castings of all groups have showed $5{\mu}m$ titanium oxide layers irrespective of sprue designs and titanium alloys. Conclusion: From the above study results, by fabricating the restorations from the centrifugal casting machine direct sprue designs revealed better castability. As we increased the number of sprues in the wax pattern, it revealed better castability. The castability of pure titanium rather than that of Ti-6Al-4V was remarkable. To fabricate the complex forms of the restorations, further researches on the efficient sprue designs and titanium alloys must be made.

• 대한치과보철학회지
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• 제44권5호
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• pp.654-664
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• 2006

Statement of problem: There has been a eat interest in the use of titanium for fixed and removable prostheses in recent because of its excellent biocompatibility. However, the melting temperature and chemical reactivity of titanium necessities casting system different from those used in conventional casting. The current titanium casting systems are based on an electric-arc design for melting the metal in an argon atmosphere and its exclusive investment. Despite the new development in Ti casting system, inadequate mold filling and internal porosity are frequently observed casting defects. Purpose : The purposes of this study were to compare the castibility and reaction layer of the casting titanium under the two casting machines and their investment condition. Material and method: coping and machine-milled titanium coping according to the casting methods and the marginal configurations. The total 28 specimens were used, and these are divided into 4 groups according to 2 casting machines and 2 investments. The castings were analyzed using x-ray microanalysis and microhardness testing. The reaction layer between margin of titanium casting and the investments was observed and analyzed with scanning electron microscope. Result: 1. Castabiliy of casting titanium specimen was best in the group of centrifugal casting machine and Selevest $CB^{\circledR}$ and good that of Selevest CB and pressure differential casting machine, Rematitan plus and centrifugal casting machine, Rematitan plus and pressure differential casting machine in order. 2. There was no significanct correlation in titanium castability in respect of casting machine. However ANOVA indicated that Selevest $CB^{\circledR}$ groups had significantly better castability than Rematitan $plus^{\circledR}$ groups.(p<0.05) 3. There was a significant microhardness difference between centrifugal casting machine groups and pressure differential groups.(p<0.05) Titanium castings in centifugal groups had significantly harder than those in pressure differential groups. 4. The addition of zirconia decreased interfacial reactivity. Conclusion: above result revealed that of the castability of titanium casting specimens had little correlation in casting machines and was better in magnesia-based investment contained ZrO2 groups. However in order to practice casting titanium in clininic, its castability should be improved, also there should be more research on factor of castability so that long-span prothesis and removable partial denture metla frame may be casted completly.

• 대한치과기공학회지
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• 제28권1호
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• pp.9-17
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• 2006

The purpose of this study was to evaluate the titanium castability with a spin type casting machine(TiCast, Super R, Selec, Osaka. Japan). We tested phosphate bonded investment "Rematitan$^{(R)}$Plus(Dentaurum, Inc., Pforzheim, Germany)"of mesh grid pattern and plate pattern. Four different mold temperatures(room temperature, 200$^{\circ}C$, 400$^{\circ}C$ and 600$^{\circ}C$) were prepared for the present study. In mesh grid pattern with spruing of $\varphi$0.88㎜ dimeter, when the mold temperature increased, high percentage of castability was gained. Mold temperature showed a highly significant(p<0.05) correlation on the castability, In plate pattern, the higher the mold temperature during casting, the greater the adhesive phenomenon between Ti surface and the investment.

• 구강회복응용과학지
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• 제27권1호
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• pp.73-79
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• 2011

연구의 목적은 타이타늄이 함유된 코발트 크롬의 주조성에 타이타늄이 어떠한 영향을 미치는지 평가하기 위함이다. 원재료에는 코발트, 크롬, 몰리브덴, 실리콘, 망간, 탄소, 질소, 티타늄이 사용되었고 이것들을 정량계량하였다. $Biosil^F$ (Degudent, Germany)를 대조군으로 하였고, 실험군에는 티타늄을 1 wt% 에서 4 wt% 까지 각기 다른 함량으로 첨가하여 주조성을 평가하였다. 왁스 패턴은 $30{\times}40$ cm 크기의 직사각형 모양으로, 총 160개의 격자를 함유하고 있다. 원심주조기 (Neutrodyne Easy Ti: Manfredy)를 사용하여 왁스패턴을 주조하였다. 주조성의 평가는 왁스패턴의 4면이 완전한 격자의 수를 육안과 X-ray를 이용하여 검사하였다. 1 wt%에서 3 wt%의 티타늄을 함유한 금속은 대조군과 비슷한 주조성을 나타냈다. 4 wt%의 티타늄을 함유한 금속은 좋지 않은 결과를 보였다. 4 wt% 미만의 티타늄 함유한 실험군의 주조성은 대조군과 비슷하면서도 기계적인 물성은 증가됨을 보였으며 임상에서의 성공적인 사용을 가능케 한다.

• 대한치과기공학회지
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• 제29권2호
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• pp.129-140
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• 2007

The purpose of this study was to evaluate the titanium castability (internal porosity) between pressure type casting machine & centrifugal casting machine with air-vent or not. Internal porosity is a well-known problem in dental titanium casting, resulting in inferior mechanical properties of dental restorations. To evaluate the castability, the square plate was chosen. 40 plate patterns($20{\times}20{\times}1.8mm$)were attached to funnel-shaped sprue. Then 20 plate patterns were attached air-vent. They were invested in titanium investment material and cast in a pressure type casting machine(20castings) and centrifugal casting machine(20castings). Each group were divided with air-vent(10castings) or not(10castings). The titanium castings were evaluated by radiographic photograph for the location of the internal porosities. The percentage porosity of each specimen was determined using standardized digital radiographs. The results were analyzed with analysis of variance and t-test for paired comparison between two groups.

• 대한치과기공학회지
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• 제29권1호
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• pp.133-138
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• 2007

In this study, the castability and of commercially pure titanium(c.p.Ti) grade according to the casting condition which are the vacuum condition in casting machine and mold temperature of investment, was investigated. Argon-arc melt/centrifugal casting machine was used for casting the specimens. The microstructure and mechanical properties were evaluated by using optical microscope. The results were as follows; 1. It could make a sure that there's relatively not much defect of casting body of c.p.Ti according to the deference of air pressure. 2. It could make sure that it formed porosity on the surface inside of the casting body of c.p.Ti according to deferent temperature. and on excellent castability was below $200^{\circ}C$ 3. As the mold temperature of investment was increased, the lamellar structure of phase and coarse grains were shown, especially under 42MPa.

• 대한치과보철학회지
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• 제45권4호
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• pp.431-443
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• 2007

Statement of problem: Injuries along with discomfort may result on the oral mucosa when non-rigid material is used as the major connector in construction of RPD, since nonrigid major connectors transmit unstable forces throughout the appliance. Titanium which recently draws attention as a substitute of Co-Cr had a difficulty in fabricating due to high melting temperature but the development of casting technique makes it possible to apply to the clinical case. Purpose: The purpose of this study was to investigate the rigidity and the castability of titanium upper major connector by design and make a comparison with Co-Cr major connectors which are widely used in clinical cases now. Material and methods: Casting was done using CP-Ti(Grage 2) (Kobe still Co., Japan) for the experimental groups, and 4 various designs namely palatal strap, U-shaped bar, A-P strap, and complete palatal plate were casted and 5 of each designs were included in each group. For the experimental group, Universal testing machine (Model 4502; Instron, Canton, Mass) was used to apply vertical torsional force vertically to the horizontal plane of major connector. In the second experiment, Vertical compressive force was applied to the horizontal plane of major connector. As a comparative group, Co-Cr major connector was equally manufactured and underwent the same experimental procedures Strain rate was measured after constant loading for one minute duration, and statistical analysis was done with SPSS ver.10.0 for WIN(SPSS. Inc. USA). From the one-way ANOVA and variance analysis (P=0.05), Scheffe's multiple comparison test implemented. Results: 1. Least amount of strain was observed with complete palatal plate followed by A-P bar, palatal bar, and the U-shaped bar having most amount of strain. 2. In all designs of titanium major connector, less strain rate was observed under compressive loading than under torsional loading showing more resistance to lateral force. 3. For titanium major connector, less strain rate was observed when the force is applied to the first premolar area rather than to the second molar area indicating more strength with shorter length of lever. 4. In Comparison of Co-Cr major connector with titanium major connector, palatal strap and U-shaped bar designs showed higher strength under torsional force that is statically significant, and under compressive force, no significant difference was observed expert for U-shaped bar. 5. In titanium major connector, complete palatal plate showed lowest success rate in casting when compared with the Co-Cr major connector. Conclusion: Above results prove that when using titanium for major connector, only with designs capable of generating rigidity can the major connector have almost equal amount of rigidity as Co-Cr major connector and show lower success rate in casting when compared with the Co-Cr major connector.

• 대한치과보철학회지
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• 제51권4호
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• pp.261-268
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• 2013

연구 목적: 본 연구는 납형의 크기 및 형태 변화가 티타늄의 주조성에 어떠한 영향을 미치는지 확인하고자 하였다. 연구 재료 및 방법: 납형의 크기에 따라 Small Pattern군과 Large Pattern군으로 나누었고, 각각 Flat, Semicircular, Horse-shoe 및 V-shape형으로 납형의 형태에 따라 4개의 하위군으로 나누어 총 8개의 군으로 분류하였다. 모든 납형의 주입선은 Runner-bar형으로 하였다. 티타늄 주조 전용 매몰재인 실리카계 매몰재(Rematitan Plus$^{(R)}$, Dentarum, Germany)를 이용하여 매몰하였고, 아크용융 방식의 원심 주조기(Ti Cast Super R$^{(R)}$, Selec, Japan)를 사용하여 주조하였다. 주조성 평가는 완전한 형태로 주조 된 격자의 개수를 척도로 재현 정도를 확인하였다. 통계처리는 SPSS ver. 19.0 for WIN (SPSS. Inc. Chicago, IL, USA)를 사용하였다. 납형의 크기 및 형태에 따른 티타늄의 주조성을 이원변량 분산분석(Two-way ANOVA)을 이용하여 분석하였다. 결과:납형의 평균 재현율은 Small Pattern군은 95.14%, Large Pattern군은 94.30%로 Small Pattern군의 주조성이 유의하게 높았다(P<.05). 납형의 형태 변화에 따른 주조성은 Small Pattern군에서 Semicircular군 133.20개(96.52%), Horse-shoe군 132.40개(95.94%), Flat군 132.00개(95.65%), V-shape군 127.60개(92.46%) 순으로 감소하였다. Large Pattern군은 Flat군 198.60개(95.94%), V-shape군 197.80개(95.56%), Semicircular군 196.40개(94.88%), Horse-shoe군 188.00개(90.82%)순으로 감소하였다. Small Pattern군과 Large Pattern군 모두에서 납형의 형태변화에 따른 주조성은 유의할 만한 차이를 보이지 않았다(P>.05). 결론:주조체의 크기가 작을수록 주조성이 높아짐을 알 수 있었고 형태에 따른 주조성에서는 큰 영향을 받지 않는 것을 알 수 있었다.

• 대한치과보철학회지
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• 제40권4호
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• pp.352-364
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• 2002

There has been a great interest in the use of titanium for fixed and removable prostheses in recent because of its excellent biocompatibility. However the high melting temperature and chemical reactivity of titanium necessitates casting systems different from those used in conventional casting. The current titanium casting systems are based on an electric-arc design for melting the metal in an argon atmosphere and its exclusive investment. Despite the new developments in Ti casting systems, inadequate mold filling and internal porosity are frequently observed casting defects. Therefore, the study on the fabrication technique including sprue design to solve these casting defects is still necessary. In this study to evaluate the effect of sprue design on the castability of simulated cast titanium crowns, 10 cylindrical cast crowns for each group with four different sprue design(Single group. Double group, Runner bar group. Reservoir group) were fabricated. An impression of the entire casting margin was made and cut at $90^{\circ}$ intervals, and the sections were photographed in a microscope at $100{\times}$ magnification to record marginal discrepancy. The internal porosities of the cast crowns were disclosed by radiographs. Within the limits of this study. the following conclusions were drawn. 1. The overall mean marginal discrepancies for each group were as follows: Double group, $43.65{\mu}m$; Reservoir group, $50.27{\mu}m$; Single group, $54.17{\mu}m$; Runner bar group, $58.90{\mu}m$ (p<0.05). 2. The mean of marginal discrepancies for wax patterns was $10.65{\mu}m$. 3 The numbers of internal porosity showed the most in Runner bar group followed by Single group, Reservoir group, and Double group.