갈륨합금과 아말감의 전기화학적 부식거동 비교

고영무,최한철,강성남,강희영,이승윤 대한치과기재학회 1998 대한치과재료학회지 Vol.25 No.3

A gallium based alloy(GA) that was developed as a substitute for dental amalgam was investigated for electrochemical corrosion behavior in 4 kinds of electrolytes(1% lactic acid, 0.05% HCI, Modified Fusayama's artificial saliva, and 0.9% NaCl). The related corroded microstructure were examined and microanalyses were conducted using ICPES. Polarization tests were conducted by scanning from -1,500㎷ to 1,000㎷(vs.SCE) at 75㎷/min. The obtained results were as follows: 1. GA showed wide passivation area next to SYB in artificial saliva, suggesting good stability. 2. The amounts of Sn, Cu released from GA were similiar to those of CAV, and decreased in the order of KAT, SYB. 3. All of specimens were observed pits at the area of pores in electrolytes containing chloride ions, and forming much corrosion products in 1% lactic acid and artificial saliva after corrosion test. 4. From the surface analyses of XRD, GA showed much corosion products containing gallium at the surface after corrosion test. In conclusion, the corrosion resistance of GA was lower than that of SYB and similiar to that of CAV and KAT.

아르곤 레이저와 가시광선에 의한 중합 후의 수복재와 치아와의 전단결합강도 비교

고영무,계기성,황호길 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.3

Previous preliminary researches have shown that argon laser will polymerize dental photo-activated resin materials. The purpose of this study was to compare the shear bond strength of dental restorative materials to teeth polymerized with an argon laser and visible light. An argon laser operating at 0.5W of power and a conventional visible light polymerization unit were used in testing shear bond strength between restorative materials and teeth. Specimens were prepared according to accepted standards for testing. A universal testing machine was used to shear bond strength 5㎜/min crosshead speed. In case of argon laser, exposure time were 10 second, whereas in case of visible light, exposure time were 40 second. The results showed that shear bond strength of F2000 Compomer(3M) polymerized with argon laser were superior to those of polymerized with visible light and there is significantly different(p<0.05). Whereas, in case of both OptiBond FL(Kerr) and Spectrum TPH(Dentsply) shear bond strength of composite resins polymerized with argon laser were slightly inferior to those of polymerized with visible light, but there is no significant difference(p>0.05). This study was supported by Research Funds from Chosun University,1996.

치과용 자성재의 안정성 개선에 관한 연구 : I. 치과용 자성재의 전기화학적 부식에 대한 스퍼터링 도금의 효과 I. Effects of Sputtered Film Deposition on the Electrochemical Corrosion of Dental Magnetic Materials

고영무,최한철,정재헌,정효수,최성욱 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.4

In order to investigate the various properties of dental magnetic materials studies on corrosion behavior, decreasing rate of magnetic flux density, amount of elements released, mean average surface roughness values and the changing of mean surface microhardness values for dental application were done. To increasing the corrosion resistance of dental magnetic materials, surfaces of Sm-Co and Nd-Fe-B based magnetic materials were plated with gold(Au), platinum(Pt), titanium(Ti), chromium(Cr) and cobalt(Co), and then electrochemical corrosion test were performed in 4 kinds of electrolyte solution(0.9% NaCl, 1% lactic acid, 0.05% HCl and modified Fusayama's artificial saliva). The results were as follows: 1. In Sm-Co and Nd-Fe-B based magnetic materials, the pitting corrosion of experimental group was higher than that of the control group, the experimental group was less corrosive than control hroup. 2. The amount of elements released from experimental group was more significantly decreased than that of control group. 3. Decreasing rate of magnetic flux density of experimental groups was significantly lower than that of control group after corrosion test. 4. The mean average surface roughness value of one(Sm-Co based magnetic materials not plated) of the control group was much increased in modified Fusayama's artificial saliva after first corrosion but that of the other(Nd-Fe-B based magnetic materials not plated) was much increased in 0.05% HCl solution. 5. The decreasing rate of surface microhardness values of experimental groups were lower than that of control group after corrosion, 6. Intergranular corrosion started first from the grain boundary of the control group and they advanced gradually to general corrosion, and the pitting corrosion occurred locally at area of existing pits in experimental group.

Vita Lumin Shade Guide와 Vita Shade Resin Composite 간의 색깔차이

고영무,최한철,최충국 대한치과기재학회 1996 대한치과재료학회지 Vol.23 No.2

The Purpose of this study was to evaluate the possibility of using Vita Lumin shade guide to select shades of composite resin. Vita Lumin shade guide, such as four kinds of composite resin; Z100(3M), Prisma T.P.H.(Caulk/Dentsply), Tetric(Vivadent), Dentacolor resin system(Kulzer Co.) and shade guide which is supplied by the manufacturer were used in this study. The four kinds of shade which are poplar were used; A2,A3,B3, and D3, but, in case of Prisma T.P.H. we chose A3.5 instead of A3 because it does not have A3 shade. The shade guide from the manufacturer and Vita Lumin shade guide are ready made but we made 6 samples od each composite resin which size are 10±1mm in diameter, 2.0±0.1mm in thickness, and then composite resin were light cured for 40 sec. In case of the Dentacolor resin system, we put them into the Dentacolor XS unit then light cured 180 sec. according to manufacturer's instruction. After the curing, we eliminated the samples from the molds and stored them in distilled water for 48 hours. Using the Colorimeter(Hunter Inc, USA) and examining the value of L*a*b* for three times, we calculated their mean values. The resulte were as follows; among all 4 kinds of composite resin which are produced by same shade, shade guide which are supplied by same shade vs. composite resin, there are big differences more than expected. In the view of the result of this study, there is a little problem with the use of the Vita Lumin shade guide and the shade guide which is supplied by munufacturer. Therefore, we conclude that we need more accurate the cuatomized shade guide. This study was supported by research funds from Chosun university.

최신 본딩재

고영무 대한치과기재학회 2000 대한치과재료학회지 Vol.27 No.4

인공타액에서 치과용 자성재의 전기화학적 부식에 대한 스퍼터링 도금의 효과

고영무,김경남,김광만 대한치과기재학회 1997 대한치과재료학회지 Vol.24 No.2

Dental magnetic materials have been applied to removable prosthetic appliances, maxillofacial prostheses, obturator and dental inplant but they still have some problems such as low corrosion resistance in oral environments. To increase the corrosion resistance of dental magnetic materials, surfaces of Sm-Co and Nd-Fe-B based magnetic materials were plated with gold(Au), platinum(Pt), titanium(Ti), chromium(Cr) and cobalt(Co), and then electrochemical corrosion test were performed in modified Fusayama's artificial saliva. From this study, corrosion behavior, decreasing rate of magnetic flux density, amount of elements released, mean average surface roughness values and the changing of mean surface microhardness values were measured comparing with control group of non-sputtered plating magnetic materials. The results were as follows : 1. In Sm-Co and Nd-Fe-B based magnetic materials, the pitting corrosion of control group was lower than that of the experimental group, the control group was more corrosive than experimental group. 2. The amount of elements released from experimental group was more significantly decreased thatn that of control group(p<0.05) 3. Decreasing rate of magnetic flux density of experimental groups was significantly lower than that of control group after first corrosion, but it was increased after second corrocion in all tested cases. 4. The mean average surface roughness value of control group were not different from those of experimental group. The mean average surface roughness value of both Sm-Co and Nd-Fe-B based magnetic materials were much increased in modified Fusayama's artificial saliva after corrosion. 5. The mean average surface microhardness values of control group were not different from those of experimental group before corrosion. After corrosion, the same valuse of contral group were more decreased that those of experimental group, and the decreasing rate of surface microhardness values after second corrosion was higher than that of values after first corrosion. 6. Intergranular corrosion started first from the grain boundary of the control group and they advanced gradually to general corrosion, and the pitting corrosion occurred locally at area of existion pits in experimental group. In conclusion, it is considered that the corrosion problem of dental magnetic materials could be solved to some extent by sputtered plating with several metals on the surface of dental magnetic materials.

불소제재가 불소유리 수복재의 색변화에 미치는 영향

고영무 大韓齒科器材學會 2000 대한치과재료학회지 Vol.27 No.3

The high reactivity of fluoride agents used in topical fluoride treatments have raised important questions on their potential adverse effects on restorative materials. The purpose of this study was to evaluate the effect of various types of fluoride agents used for dental office and home treatments on the color change of some polyacid-modified resin composite(Compoglass and Dyract) and the resin-modified glass ionomer(Fuji Ⅱ LC). Each specimen was treated with 4 kinds of fluoride agents for 4 minutes every day until 8 weeks. The color change was measured using specimens aged up to two months with colorimeter. The resulted were as follows; 1. The color change of resin-modified glass ionomer cement Fuji Ⅱ LC was greater than any other material. 2. The color change of 3 kinds of materials were greatest in contact with 8% SnF₂solutions. 3. It showed greater color change in case of materials immersed in fluoride agents than materials immersed in water. In conclusion, Topically applied fluorides induced adverse effects on the color change characteristics of resin-modified glass ionomer cement and polyacid-modified composite resins suggesting that fluoride agents effective in limiting caries should be used with caution with patients who have aesthetic restoratives.

최과 교정용 스테인리스 강 선재의 신선 가공법이 내식성에 미치는 영향

고영무,모웅남,최한철 大韓齒科器材學會 2003 대한치과재료학회지 Vol.30 No.1

The dental orthodontic wire requires good mechanical properties, such as elastic strength, combined with a high resistance to corrosion. For increasing elastic strength and delaying onset of stress corrosion cracking, drawing methods(one-step and two-step drawing) have been used in this study to extend service life of metal components, However, there is no information on the electrochemical corrosion behavior of drawn wires for orthodontics. To increase elastic strength, good corrosion resistance, and biocompatibility, the electrochemical characteristics of drawn wire have been researched by field emission scanning microscope and potentiodynamic method in 0.9% NaCl solution. The one-step drawn wire showed the formation of rough surface. The hardness and tensile strength of two-step drawn wire increased. Electrochemical measurements showed that, in the case of two-step drawn wire, the corrosion resistance and pitting potential increased compared with two-step drawn wire due to the drawing induced small surface roughness, such as scratch, whereas passivation and active current density decreased as the reduction in area for drawing increased.

전해액의 종류에 따른 치과용 금합금의 전기화학적 부식 거동

고영무,최성욱 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.1

The effect of different electrolytes on the results from potentiodynamic polarization corrosion testing was studied for 3 different dental gold alloys. The obtained results were as follows. 1.From the potentiodynamic curves the corrosion behavior of natural saliva was similar to that of Darvell's and Hay & Hartles' artificial saliva solution. 2.Fusayama's and Tani & Zucchi's artificial saliva solutions were more corrosive than natural saliva, Darvell's and Hay & Hartles' artificial saliva solution. 3.The corrosion behaviors of Fusayama's and Tani & Zucchi's artificial solutions were very similar in case of Cast-1 and Cast-3. 4.3 kinds of all alloys showed that the amount of gold released was highest in Fusayama's artificial saliva solution. In conclusion, the corrosion behavior of natural saliva was similar to Darvell's and Hay & Hartles' artificial saliva and Fusayama's artificial saliva solution was the more corrosive than any other solutions. But the effect of different electrolytes the corrosion behavior of high gold alloys was not different highly.

Dentacolor Resin System의 색안정성 및 물흡수도에 관한 연구

고영무,정재헌,최유석 大韓齒科器材學會 1995 대한치과재료학회지 Vol.22 No.2

The purpose of this study was to measure the color stability and water sorption of Dentacolor resin system at various time intervals over 6 week period. Ten, 20 x 1mm discs of the resin specimen were prepared according to ADA specification No.27 and cured with a photo-polymerization equipment(Dentacolor XS and Unilux AC). The color parameters of L*, a*, b* were measured with a computerized colorimeter(Hunter Associates Laboratory Inc., USA) in the transmittance mode. The total color change(ΔE) occurred during two different time periods was calculated using the following equation: ?? The amount of water sorption measurements was done in accordance with ADA specification No.27 for one week in distilled water at 37 ±1℃ and then stored extended up to 6 weeks. The obtained results were as follows : l. At first week, total color difference(ΔE) value of Dentacolor resin system was 1.430 ±0.664. 2. It was found that the range of total color difference(ΔE) of Dentacolor resin system was between 0.5∼1.430 for 6 weeks. 3, The amount of water sorption for one week was 0.30 ±0.119mg/cm²and it was lower than the 0.7mg/cm²/week for type Ⅱ composites in ADA specification No.27. 4. The amount of water sorption of Dentacolor resin system after 6 weeks was much more than its amount of water sorption of the first week, but it was not significant difference(p>0.05).