• 대한치과교정학회지
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• 제14권2호
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• pp.241-248
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• 1984

The mechanical properties of Cr-Ni alloy of austenitic stainless steel and Co-Cr alloy orthodontic wires were studied in tension. The wires (0.018 inch) were tested in the as-manufactured and heat-treated conditions. Instron type tension testing machine was used for this study. Mean values and standard deviations were computed. The results were as follows; 1. The Cr-Ni orthodontic wires of austenitic stainless steel are generally superior than the Co-Cr orthodontic wires in ultimate tensile strength, In the elongation, however, Co-Cr orthodontic wire are superior than Cr-Ni orthodontic wires. 2. Increase in the degree of strength by heat treatment are more clearly shown in Co-Cr orthodontic wires than Cr-Ni orthodontic wires. And the elongation is decreased by heat treatment in both case. 3. The changes of the degree of strength by cooling method we not clearly shown, but in Cr-Ni orthodontic wires, air cooling are more effective, in Co-Cr orthodontic wires, cooling effect are scarcely shown.

• Imaging Science in Dentistry
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• 제45권3호
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• pp.159-168
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• 2015

Purpose: This study was performed to compare the metal artifacts from common metal orthodontic brackets in magnetic resonance imaging. Material and Methods: A dry mandible with 12 intact premolars was prepared, and was scanned ten times with various types of brackets: American, 3M, Dentaurum, and Masel orthodontic brackets were used, together with either stainless steel (SS) or nickel titanium (NiTi) wires. Subsequently, three different sequences of coronal and axial images were obtained: spin-echo $T_1$-weighted images, fast spin-echo $T_2$-weighted images, and fluid-attenuated inversion recovery images. In each sequence, the two sequential axial and coronal images with the largest signal-void area were selected. The largest diameters of the signal voids in the direction of the X-, Y-, and Z-axes were then measured twice. Finally, the mean linear values associated with different orthodontic brackets were analyzed using one-way analysis of variation, and the results were compared using the independent t-test to assess whether the use of SS or NiTi wires had a significant effect on the images. Results: Statistically significant differences were only observed along the Z-axis among the four different brands of orthodontic brackets with SS wires. A statistically significant difference was observed along all axes among the brackets with NiTi wires. A statistically significant difference was found only along the Z-axis between nickel-free and nickel-containing brackets. Conclusion: With respect to all axes, the 3M bracket was associated with smaller signal-void areas. Overall, the 3M and Dentaurum brackets with NiTi wires induced smaller artifacts along all axes than those with SS wires.

• 대한치과교정학회지
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• 제45권3호
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• pp.130-135
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• 2015

Objective: In our previous study, glass-fiber-reinforced plastics (GFRPs) made from polycarbonate and glass fibers were prepared for esthetic orthodontic wires using pultrusion. These laboratory GFRP wires are more transparent than the commercially available nickel-titanium wire; however, an investigation of the color stability of GFRP during orthodontic treatment is needed. Accordingly, in the present study, the color stability of GFRP was assessed using colorimetry. Methods: Preparation of GFRP esthetic round wires (diameter: 0.45 mm [0.018 inch]) using pultrusion was described previously. Here, to investigate how the diameter of fiber reinforcement affects color stability, GFRPs were prepared by incorporating either $13-{\mu}m$ (GFRP-13) or $7-{\mu}m$ glass (GFRP-7) fibers. The color changes of GFRPs after 24 h, and following 1, 2, and 4 weeks of coffee immersion at $37^{\circ}C$, were measured by colorimetry. We evaluated the color stability of GFRPs by two evaluating units: the color difference (${\Delta}E^*$) and National Bureau of Standards (NBS). Results: After immersion, both GFRPs showed almost no visible color change. According to the colorimetry measurements, the ${\Delta}E^*$ values of GFRP-13 and GFRP-7 were 0.73-1.16, and 0.62-1.10, respectively. In accordance with NBS units, both GFRPs showed "slight" color changes. As a result, there were no significant differences in the ${\Delta}E^*$ values or NBS units for GFRP-13 or GFRP-7. Moreover, for both GFRPs, no significant differences were observed in any of the immersion periods. Conclusions: Our findings suggest that the GFRPs will maintain high color stability during orthodontic treatment, and are an attractive prospect as esthetic orthodontic wires.

• 대한치과교정학회지
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• 제33권6호
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• pp.465-474
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• 2003

형상기억효과 및 초탄성 특성을 가진 니켈 타이타늄 와이어는 대단히 다양한 제품들이 출시되어 있어서, 보다 적절하면서도 경제적인 재료를 선택하고자 하는 임상가에게 어려움을 주고 있다. 이때, 교정 선재의 기계적 특성에 대한 실험적 연구는 임상가에게 유용한 정보를 제공해 줄 수 있다. 이 연구에서는 5군으로 나뉘어진 4종의 교정선재(stainless steel, multistranded, superelastic nickel titanium 그리고 themoactivated nickel titanium)에 대한 응력 -변형 실험을 통한 기계적 특성에 대한 비교를 시행하였다. 각 군의 교정선재에 대하여 일련의 여섯 가지 실험이 이루어졌다. 처음에는, 각 군에 대하여 선재가 파절될 때까지, 3차례의 실험이 이루어졌다. 그리고, 각 군에서 세 종류의 실험이 이루어졌는데, 표준하중에서 선재를 신장시켜서, 하중을 주었을 때와 하중을 제거하였을 때의 기계적 특성에 대한 신뢰할 만한 비교를 시행하였다. 각 군간의 차이를 알아보기 위하여 t-test를 시행하였다. 실험결과, 생리적인 치아이동을 위한 기계적 특성, 즉 강성, 탄성률, 힘의 발휘 특성 등을 고려해 볼 때, themoactivated nickel titanium, multistranded wire, stainless steel wire 순으로 바람직하였다. 초탄성은 superelastic nickel titanium에서 나타났다. 섭씨 37도에선 themoactivated nickel titanium의 형상기억효과가 나타났는데, 이것은 온도가 기계적 특성을 증진시키는데 중요하다는 것을 보여준다.

• 대한치과교정학회지
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• 제15권2호
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• pp.163-174
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• 1985

The requirements of orthodontic wire should include chemical stability, non-discoloration and non-corrosion in oral environment. Ability to be soldered, ease of fabrication and elasticity should be also considered. The purpose of this study was to compare and analyze the physical properties of Tru-chrome wire and manufactured E.S.S. (Experimental Stainless Steel) wire similar to Tru-chrome. The results were as follows: 1. Tru-chrome wire and E.S.S. wire were SUS 304 which was 18 Cr-8Ni austenite stainless steel. There was not significant difference in each composition between two wires. 2. There were not significant differences in ultimate tensile strength, yield strength, elongation and modulus of elasticity between Tru-chrome and E.S.S. wires. 3. There was not significant difference between flexuree modulus of elasticity of Tru-chrome and E.S.S. wires. 4. Micro-hardness value of E.S.S. wire was more than that of Tru-chrome wire and they were softened significantly by solution heat reatment. 5. Micro-structure of Tru-chrome and E.S.S. wires showed fibrous interlocking grains, and an austenite structure after solution heat treatment. 6. There was significant difference between corrosion rate of Tru-chrome and E.S.S. wires.

• 대한치과교정학회지
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• 제26권5호
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• pp.591-599
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• 1996

본 연구는 널리 이용되고 있는 두 종류의 교정용 호선에 다양한 처리를 가한 후 호선의 세포독성을 비교, 평가하고자 시행하였다. 018x025 inch 굵기의 stainless steel 호선과 Co-Cr 호선을 실험 재료로 선택하여 stainless steel 호선을 A 호선, Co-Cr호선을 B 호선이라 칭하였으며 각각의 호선을 다시 가해진 처리에 따라 4군으로 나누었다. A-1군과 B-1군은 제작된 상태 그대로의 호선을 이용하였으며 A-2, B-2군은 기기를 이용하여 $850^{\circ}\;F$에서 4분간 열처리하였다. A-3, B-3군은 같은 방법으로 열처리한 후 표면의 불순물을 제거하기 위해 전해연마를 시행하였고 A-4, B-4군은 소량의 은납(Ag-solder)을 납착(soldering) 하였다. 사람의 치은 섬유아세포를 배양하고 agar overlay법을 이용하여 각군의 호선의 세포독성을 검사하였으며 세포독성을 반응지수(탈색지수/용해지수)로 평가하여 다음의 결론을 얻었다. 1. stainless steel 호선과 Co-Cr 호선 모두 제작된 그대로의 상태에서는 세포독성을 나타내지 않았다. 2. 두 호선에 대한 열처리나 전해연마는 호선의 세포독성에 영향을 미치지 못하였다. 3. 은납이 납착된 stainless steel호선은 은납이 납착된 Co-Cr호선에 비해 더 넓은 범위의 탈색을 나타냈으나 탈색지수와 세포독성(반응지수)에서는 차이를 보이지 않았다. 4. 은납이 납착된 호선은 두 호선 모두에서 중증도의 세포독성을 나타냈다.

• 대한치과보철학회지
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• 제34권4호
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• pp.823-832
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• 1996

The purpose of this study was to assess the effect of 1) the diameter(0.7,1.0,1.2mm) and number(1,2,3) of commonly available orthodontic metal wires embedded in self-curing orthodontic acrylic resin specimens($64{\times}10{\times}3mm$) and 2) the use of chemical adhesive system(Silicoater, Metalprimer) to prevent slipping at the interface between the resin and the metal wire on reinforcement by using three-point bending test. From this study, the following results were obtained. 1. No statistically significant difference was found among the transverse strengths for the control without reinforcement, one 0.7mm wire, two 0.7mm wires, three 0.7mm wires, and one 1.0mm wire groups(P>.05). 2. In the groups with 1.0 or 1.2mm wires, the transverse strength increased in proportion to the increase of number of wires(P<.05). 3. In the groups with 0.7 or 1.0mm wires, neither of Silicoater and Netalprimer increased the transverse strength significantly(P>.05). 4. No statistically significant difference was found in transverse strength between Silicoater groups and Metalprimer groups with same diameter of wires(P.>05). From these result, it is concluded that diameter of wires is a primary considering factor to reinforce the acrylic resin effectively and, when this requirement is satisfied, increased number of wires or chemical adhesive systems can be expected to produce the additional reinforcing effect.

• 대한치과교정학회지
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• 제24권1호
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• pp.87-94
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• 1994

The purpose of this study was to evaluate the torque effect of othodontic wires. Ten types of orthodontic wires (five types of materials, two types of cross-sectional dimensions) were selected. Each group of ire type was constituted with five specimens. These specimens were tested on the universal testing machine(Instron) with specially-designed jig. The torque-twist curve of each wire was obtained and the results were analyzed statistically. The results were as follows. 1. 0.017'$\times$ 0.025' wire showed more torque effect than 0.016'$\times$ 0.022' wire at the same twist. 2.Torque effect was the greatest in stainless steel and the least in Nitinol. 3.The maximum amount of torque was the greatest in heat-treated Blue Elgiloy and the least in Nitinol.

• 대한치과교정학회지
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• 제30권5호
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• pp.613-623
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• 2000

교정용 브라켓과 교정선 사이의 마찰력에 관련된 요소들에는 브라켓의 종류, 교정선의 재질과 형태, 결찰방법의 차이, 건조환경과 타액환경의 차이, 브라켓간 offset의 차이, 브라켓간 거리, 이동속도 등이 있다. 이러한 요소들에 따른 마찰력의 변화를 비교, 분석하여 각 요소들 간의 관계를 알아보고자 본 연구를 하였다. 8종류의 0.018"x0.025"상악 견치와 상악 제2 소구치용 브라켓을 슬라이드 위에 부착시키고 0.016 및 0.016"x0.022" 스테인레스 스틸 교정선과 같은 크기의 NiTi 교정선 및 Cu-NiTi 교정선을 이용하여 서로 다른 조건에서 마찰력을 측정하여 다음의 결과를 얻었다. 1. 브라켓의 종류에 따른 마찰력의 차이는 Polycrystalline세라믹 브라켓인 Allure의 평균 마찰력이 가장 높게 나타났고, 세라믹과 합성된 플라스틱 브라켓인 Vogue, 금속 브라켓인 Mini-Twin, 금속 슬롯을 갖는 플라스틱 브라켓인 Elan, monocrystalline 세라믹 브라켓인 Starfire, single 브라켓인 Lewis/Lang, 자가결찰 브라켓인 SPEED의 순으로 감소하였으며, frictionless 브라켓인 Shoulder의 평균 마찰력이 가장 낮았다. 자가결찰 브라켓은 원형 교정선에서는 낮은 마찰력을 나타냈고, 사각형 교정선에서는 높은 마찰력을 나타냈다. 2. 교정선 재질에 따른 평균마찰력은 스테인레스 스틸 교정선이 다른 교정선들에 비해 통계학적으로 유의하게 낮았으며, NiTi 교정선, Cu-NiTi 교정선 순으로 평균 마찰력이 높았다. 교정선의 형태에 따른 마찰력은 원형 교정선의 평균마찰력이 각형 교정선보다 낮았다. 3. 본 연구에서 스테인레스 강으로 결찰했을 때의 평균마찰력이 탄성모듈로 결찰했을 때에 비해 모든 조건에서 통계학적으로 유의하게 높았다. 4. 건조환경에서의 금속 브라켓에 스테인레스 스틸 교정선, NiTi 교정선 및 Cu-NiTi교정선의 평균마찰력은 타액환경에서 보다 유의하게 낮았다. 5. 브라켓간 offset이 증가함에 따라 평균마찰력은 유의하게 증가하였다. 6. 브라켓간 거리의 변화에 대한 마찰력의 차이는 교정선의 재질에 따라 차이가 나며, 스테인레스 스틸 교정선은 브라켓간 거리가 감소할 때 마찰력이 유의하게 변화하지 않았으나, NiTi 교정선의 경우는 유의하게 증가하였다. 7. 브라켓내의 교정선의 이동속도에 따라 마찰력은 유의하게 변화하지 않았다. 이상의 결과로 볼 때 교정 치료동안 적정 교정력을 유지하기 위해 자가결찰브라켓, 스테인레스 스틸 교정선과 탄성모듈결찰법을 사용하는 것이 유리하며, 치료시기에 따라서 요구하는 마찰력이 다르므로 상황에 따라 재료를 선택하는 것이 중요할 것으로 사료된다.

• 대한치과교정학회지
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• 제20권2호
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• pp.381-390
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• 1990

The purpose of this study was to evaluate the effects of heat treatment on mechanical properties in $0.016^{{\prime}{\prime}}{\times}0.022^{{\prime}{\prime}}$ blue Elgiloy wires and to measure the amounts of nickel and chromium released from the wires in artificial saliva. Ultimate tensile strength, yield strength and elongation were measured with universal testing machine (Instron). and the amounts of nickel and chromium released from the sample were measured with atomic absorption spectrophotometer after one week immersion in the artificial saliva. Ultimate tensile strength and yield strength were progressively increased below $1000^{\circ}F$, but elongation was decreased. And the results were reversed above $1100^{\circ}F$. After heat treatment of the sample for 9 minutes at $1000^{\circ}F$, the maximum tensile strength and yield strength were $213.6kg/mm^2$, $140.1kg/mm^2$, respectively. Both tensile strength and yield strength were decreased progressively above $1100^{\circ}F$. Elongation was appeared the minimum value (8.6%) after heat treatment for 9 minutes and 12 minutes at $1000^{\circ}F$. There was a pronounced increase in nickel and chromium liberation with increasing time and temperature. The maximum amounts of nickel and chromium released form the sample were $4.947{\mu}m/cm^2$, $3.088{\mu}g/cm^2$, respectively after heat treatment for 12 minutes at $1300^{\circ}F$. Heat treatment is applied to orthodontic wires, especially cobalt-chromium alloys, for the purpose of stress-relievning and hardening. When the heat-treatment of orthodontic wires, the heating procedure should be well controlled in order to have no effect on corrosion resistance and mechanical properties.