• 대한치과기공학회지
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• 제21권1호
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• pp.55-65
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• 1999

So far, I Conducted an examination with focus on the type, characteristic, and test methods of impact test. which is a type of mechanical that evaluate materials. As mentioned previously, in testing soldering strength of soldering is the load when the object under experiment is broken down with the result of flexibility test or peel test. In this method, a hevay load is necessary until alloy of parent metal is bended, if the alloy of the parent metal has a large mechanical quality(peel strength or resisting power). Once the alloy of the parent metal is bended, however, it tends to come into pieces abruply form the part where soldered. Therefore, a metal has a high breakdown value if the degree of strength of its parent metal is high even if the result of measurement indicates otherwise. Thus, the result of the test did not correspond to the clinical result. Therefore, this study concludes as the following from a test of strength of soldering by mean of conducting an impact test, which is a type of mechanical evaluation methods : 1. Among various impact tests, a charpy thpe is more appropriate than the izod type in testing strength of soldering. 2. As far as test piece is concerned, to use subsized impact test piece is appropriate in the impact test in that it does not have notch. 3. In the matter of analysis, it is appropriate to measure absorbing energy which results from rupture of test piece.

• 대한치과기공학회지
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• 제8권1호
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• pp.85-90
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• 1986

The effect of splinting on aqbutment tooth distal movement was performed in vitro study. An acrylic resin mandibular model with missing 2nd premolars, molars and a removable partial denture framework were constructed. The roots of the canines, 1st premolars and edentulous ridges were coated with silicone rubber. A modified Ney Surveyor was used for vertical load appkication, and abutment tooth distal movement were measured with a dial gauge with four conditions of splinting methods were tested by applying unilateral vertical loadings. The results are follows; 1. The magnitude of abutment tooth distal movement on the non-load side was less 40$\sim$69% than that occurred on the load side. 2. On the load side, reducing effect of splinting on abutment tooth movement in the condition of load side double abutment(30%), non-load side double abutment(10%), double abutments of both sides(40%) was compared with single abutments of both sides. 3. On the non-load side, reducing effect of splinting on abutment tooth movement in the condition of load side double abutment(5%), non-load side double abutment(22%), double abutments of both sides(59%) was compared with single abutments of both sides. 4. The magnitude of abutment tooth distal movement in the condition of double abutments of both sides was less 40$\sim$59% than that in the condition of single abutments of both sides.

• 대한치과기공학회지
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• 제29권2호
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• pp.151-161
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• 2007

To obtain the information of dental arch size and the distance from one tooth center to adjacent tooth center of occlusal surface of each tooth which is perforated by Pindex system on working cast for removable die system, 600 dental casts in Busan were examined. The distance of center of occlusal surface of each tooth and dental arch size were digitized. The results were as follows; 1. Mean values of the distance from center of maxillary central incisor to maxillary lateral incisor(tooth number 11$\sim$12, 21$\sim$22) is 5,7 mm, 12$\sim$13(22$\sim$23) is 5.9 mm, 13$\sim$14(23$\sim$24) is 6.9 mm, 14$\sim$15(24$\sim$25) is 7.1 mm, 15$\sim$16(25$\sim$26) is 8.4 mm, 16$\sim$17(26$\sim$27) is 10.2 mm, 11$\sim$21 is 7.30 mm. Mean values of the distance from center of mandibular central incisor to mandibular lateral incisor(tooth number 31$\sim$32, 41$\sim$42) is 4.5 mm, 32$\sim$33(42$\sim$43) is 4.8 mm, 33$\sim$34(43$\sim$44) is 6.3 mm, 34$\sim$35(44$\sim$45) is 7.2 mm, 35$\sim$36(45$\sim$46) is 9.2 mm, 36$\sim$37(46$\sim$47) is 10.7 mm, 31$\sim$41 is 4.7 mm. 2. Mean values of the distance from the center of maxillary right central incisor to the center of maxillary left central incisor(11$\sim$21) is 7.3 mm, 12$\sim$22 is 18.2 mm, 13$\sim$23 is 26.9 mm, 14$\sim$24 is 37.2 mm, 15$\sim$25 is 43.2 mm, 16$\sim$26 is 48.5 mm, 17$\sim$27 is 53.5 mm. Mean values of the distance from the center of mandibular right central incisor to the center of mandibular left central incisor(31$\sim$41) is 4.7 mm, 32$\sim$42 is 13.3 mm, 33$\sim$43 is 21.7 mm, 34$\sim$44 is 31.9 mm, 35$\sim$45 is 38.2 mm, 36$\sim$46 is 44.8 mm, 37$\sim$47 is 50.7 mm. 3. Mean values of the distance from the line of between 11$\sim$21 to 12$\sim$22 is 10.9 mm, 12$\sim$22 to 13$\sim$23 is 8.7 mm, 13$\sim$23 to 14$\sim$24 is 10.3 mm, 14$\sim$24 to 15$\sim$25 is 6.0 mm, 15$\sim$25 to 16$\sim$26 is 5.3 mm, 16$\sim$26 to 17$\sim$27 is 5.0 mm. 31$\sim$41 to 32$\sim$42 is 8.6 mm, 32$\sim$42 to 33$\sim$43 is 8.4 mm, 33$\sim$43 to 34$\sim$44 is 10.2 mm, 34$\sim$44 to 35$\sim$45 is 6.3 mm, 35$\sim$45 to 36$\sim$46 is 6.6 mm, 36$\sim$46 to 37$\sim$47 is 5.9 mm. 4. We checked the bottom side of cast to verify the position of dowel pin. There is no difference upper side and lower side.

• 대한치과기공학회지
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• 제5권1호
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• pp.19-26
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• 1983

I got a conclusion as a result of that in case of constructing a full denture using acrylic resin teeth, porcelain teeth, and forming posterior occlusal surface of the artificial teeth by Type III Gold and Nickel crome alloy thus construdting a full denture and therefore comparing the above case with abrasion of Natural teeth. The result were as follows : 1. The abrasion of Natural teeth and the abrasion of full denture constructed by Type III gold has a close resemblance. 2. The one that has the hightest degree of abrasion is full denture that's using, with acrylic resin teeth, maxillary and mandibular And the lowest abrasion is natural teeth-natural teeth. 3. In case of single denture, that's opposing to natural teeth, the one that has the hightest degree of abrasion is a full denture that's using Acrylic resin teeth and the lowest abrasion is a full denture that's forming occlusal surface by Type III gold. 4. The single denture, which is opposing to type III gold teeth, was abraded above everything by full denture which is constructed by porcelain teeth. 5. In the same teeth, the abrasion of mandibular teeth was greater than that of mandibular teeth was greater than that of maxillary teeth. 6. The abrasion degree of Acrylic resin teeth has no direct mutual connection with material hardness which is opposing to.

• 대한치과기공학회지
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• 제30권1호
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• pp.9-15
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• 2008

An investigation was carried out to examine the pores of casting bodies depending on the position of wax pattern in the ring for precious alloy by optical micrographs. From the result of optical micrographs, many pores were found in the Group C that wax pattern is placed in the center of the ring. However, any pores were scarcely found in the Group A, B, D and E that wax patterns are placed out of the center of thermal zone. In comparison with the pores of casting bodies of Group C, many pores were found at the cusp area rather than at the proximal surface. From these examination, it was concluded that wax pattern should be placed out of the center of thermal zone to prevent casting boies from occurring pores.

• 대한치과기공학회지
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• 제15권1호
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• pp.5-25
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• 1993

Effects of hydrogenation on microstructure and mechanical properties of pure Ti and Ti-0.15Pd alloy have been studied by means of optical microscopy, differential scanning calorimeter(DSC), Xray diffraction and micro vicker's hardness test. Grain size of pure Ti and Ti-0.15Pd alloy decresed largely by hydrogenation finer than that of pure Ti and the grain size refinement was evedent in Ti-0.15Pd alloy than that in pure Ti. Ti-.015Pd alloy carried out solution treatment at 950$^{\circ}C$, the transformation of $\alpha$' martensite was occured. The amount of Hydrogen absorption in Ti-.015Pd alloy was higher than that in pure Ti. Decomposition of hydride in pure titanium and Ti-0.15Pd alloy increased largely by hydrogenation, and micro vicker's hardness of Ti-.015Pd alloy was largely than that of pure Ti by 30% after hydrogenation. The micro vicker's hardness of Ti-0.15Pd alloy after solution treatment and dehydrogenation were higher at $\beta$ phase ranger(950$^{\circ}C$) than that phase range(750$^{\circ}C$).

• 대한치과기공학회지
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• 제8권1호
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• pp.23-29
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• 1986

One of the primary advantage of acrylic resin teeth is their ability to bond chemically to the denture base resins. But, occasionally, failure have been observed in which acrylic resin teeth break lose from the denture, indicating that chemical bonding does not always occur. The most probable explanation for this type of failure was the presence of a trace of wax remaining as a residue on the surfaces of the teeth after the boiling-out procedure which adgered to the tooth surface and prevented bonding. The purpose of this stdy was preparing the specimens of denture base resin with acrylic resin teeth that four treatment method to ridge lap portion of the tooth and investigated bond between the teeth and denture base resin with tensile strength. Compared results of tensile strength on test specimens were as follows: 1. The mean of strength among the four test groups showed the difference was significant enough(P 0.01). The order of its strength mean was methylene chloride treatment group, detergent solution treatment group, kerosene-ether treatment grgoup, boiling water only group. 2. In compared results between the wax eliminating method groups, there were significant difference between the boiling water only group and other groups(P 0.01), no significant difference were found in the wax eliminating method groups except boiling water only group(P 0.05).

• 대한치과기공학회지
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• 제22권1호
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• pp.39-47
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• 2000

This study is the know the difference bond strength according to painting method of Opaque porcelain. Among Porcelain powder for Porcelain, Noritake powder, Bonding agent 1 class and metal are selected as Base metal alloy. And painting method of Opaque porcelain is divided by 4 groups : PG, WG, NG and DG. Also it is to manufacture 24 sheets of Specimen by 6 each every method and to measure Crack-initiation Strength of Metal-porcelain and it is to observe it by Scanning electron microscope. I come to get a conclusion as follows. 1. As for Debonding strength of every experiment groups, it showed that WS group which executed Wash bake had highest value, 44.25MPa and NG group which used Normal powder had value, 42.11MPa and DG group which used Bonding agent had value, 35.88MPa and PG group which used Paste opaque had value, 35.39MPa. 2. In four painting methods of Opaque porcelain, PG group, WG group, NG group and DG group, there is no significant difference statistically in Crack-initiation Strength. 3. As a result of observing fracture surface with Scanning electron microscope, it was showde that PG group remained a lot of particle of porcelain on the surface of metal than WG group, NG group and DG group.

• 대한치과기공학회지
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• 제33권4호
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• pp.391-402
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• 2011

Purpose: The purpose of this study was to investigate the factors affecting oral health impact profile. Methods: Subjects included elderly in the metropolitan areas of the cities of Daegu and Gyeong-buk. Statistical analysis was done using the Statistical Package for Social Sciences version 19.0 for Windows. We determined frequencies and percentage, calculating means, and standard deviations, and determining statistical significance using T-tests, analysis of variance, multiple regression analysis. Results: The results of multiple regression analysis between the oral health impact profile and the related factors indicated that Occupation, Economic status are the major component oral health impact profile in general characteristics and the Impediment of oral health promotion behavior is the major component that contribute the oral health impact profile in oral health belief. Conclusion: The comprehensive and reliable research which measures oral health impact profile of elderly is necessary.

• 대한치과기공학회지
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• 제23권2호
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• pp.223-230
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• 2002

Pure titanium and Ti6Al4V alloy have been mainly used as implant materials but the cytotoxicity of V, neurotoxicity of Al resulting in Alzheimer disease had been reported. This paper was described the influence of composition of Ti-Nb alloys with 3 wt%Nb, 20 wt%Nb on the microstructure and corrosion resistance. Specimens of Ti alloys were melted in vacuum arc furnace and homogenized at $1000^{\circ}C$ for 24hr. The alloys were rolled in $\beta$ and ${\alpha}+{\beta}$ regions. The corrosion resistance of Ti alloys were evaluated by potentiodymic polarization test in 0.9% NaCl and 5% HCl solutions. The results can be summarized as follows: 1. The microstructure was transformed from $\alpha$ phase to ${\alpha}+{\beta}$ phase by adding Nb 2. The hardness of Ti-20Nb alloy was greater than Cp- Ti, Ti-3Nb alloy. 3. The corrosion resistance of Ti-20Nb alloy was better than that of Cp-Ti, Ti-3Nb alloy in 0.9%NaCl and 5%HCl solutions.