생체재료용 초내식성 스테인리스강의 이온용출특성 및 생체적합성

오근택,김금진,황충주,박용수,김경남 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.5

플라즈마 용사에 의한 다공성 초내식성 스테인리스강 코팅층의 생체내 매립용으로서의 특성에 미치는 후열처리의 영향

오근택,박용수 ( Keun Taek Oh,Yong Soo Park ) 한국부식방식학회 1998 Corrosion Science and Technology Vol.27 No.4

Bone ingrowth향상을 위한 초내식성소재의 다공성 코팅층 특성에 관한 연구

오근택,박용수,권식철 한국표면공학회 1995 한국표면공학회 학술발표회 초록집 Vol.1995 No.-

치과 급속 교정용 초내식성 스테인리스강 가공재의 특성

오근택,김영식,김경남 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.1

When stainless steels are used in the human body, the nickel ion released from the alloys over a short or long term can cause such adverse effects as allergies, dermatitis, asthma. Although the higher the corrosion resistance of stainless steels and the lower the nickel content, the better it is for the human body, since nickel has an essential role in the stabilization of the austenitic phase and the corrosion resistance of stainless steels, it is difficult to remove nickel completely. In this regard, the purpose of this study was to investigate corrosion resistance, cytotoxicity and mechanical properties of super stainless steels, and upon this basis, to evaluate their potential for orthodontic applications. Super austenitic stainless steels had higher content of nickel(17~20 wt%) than super duplex stainless steels (7~10 wt%) or super ferritic stainless steels (lower than 3 wt%). Super austenitic and duplex stainless steels had nitrogen content of above 0.2 w%. These steels had high Mo or W contents of which synergistic effect together with N increases localized corrosion resistance. In terms of hardness, super stainless steels exhibited higher value than 316L S. S. and two times higher than cp Ti(grade II). Austenitic and duplex stainless steels exhibited better mechanical properties. Super stainless steels exhibited low passive current density (3~4 μA/㎠) and similar potentiodynamic polarization behaviors among themselves. Thus, these steels are considered to have high corrosion resistance in the human body-simulated solution. Pitting corrosion occurred in 316L S. S.. A3 containing the highest nickel content, as well as SAF2507 exhibited none cytotoxicity, and the others, slightly. This indicates that the cytotoxicity has no direct relation with nickel content itself in these alloys. Super stainless steels with both high corrosion resistance and good biocompatibility are expected to be used for orthodontic applications by virtue of the passive film attribute enhanced by synergistic effect of Mo+N or by high addition effect of Cr+W.

토끼 간에 유발한 VX2암종에서 Gd-BOPTA 조영증강 MRI 지연기 영상의 유용성과 적합한 영상기법의 선택

오근택,김대현,이현근,김은성,이순노 대한자기공명기술학회 2002 대한자기공명기술학회지 Vol.12 No.-

치과용 합금의 부식 특성에 관한 연구

오근택,김명화,최병갑,김경남 大韓齒科器材學會 2002 대한치과재료학회지 Vol.29 No.1

For the aesthetic and functional restoration of edentulous patients, recently dental implants have been used widely. Dental implants and restorative alloys are required with the high corrosion resistance. Therefore, Ti and its alloys have been used as implant materials and gold, silver, Ni-Cr and Co-Cr alloys and dental restorative materials due to their high corrosion resistance. However, they can be corroded in the oral cavity that is very complicated environments. In this study, Ti G2 and G3, gold, silver, Co-Cr and Ni-Cr alloys were investigated for their corrosion resistances and phenomena. Potentiodynamic and potentiostatic tests(open circuit potential and current density at-250, 0 and 250 mV(SCE) were performed in artificial saliva at 37℃. Corrosion of gold and silver alloys did not occur in artificial saliva due to their i㎜unity in this environment. Co-Cr, Ni-Cr and pure Ti exhibited the high corrosion resistance by their own passivity. Gold, silver and Ti G2 exhibited the highest corrosion resistance, Ni-Cr alloy and Ti G3 did the relatively high corrosion resistance, and Co-Cr alloy did the low corrosion resistance. The open circuit potentials of gold, Ti G2, Ni-Cr and silver alloys were about 50, 20, 0 and -60 mV(SCE), respectively. The open circuit potentials of Ti G3 and Co-Cr decreased with the i㎜ersion time. In the potential loading of -250 mV, cathodic current flowed to all samples, although the absolute values were different. In the potential loading of 0 mV, cathodic current flowed to the others except for Co-Cr alloy. Ti G2 and Co-Cr alloys showed anodic current and the others cathodic current in the potential loading of 250 mV. If the pure Ti is used as dental implant in the oral cavity, gold and silver alloys are considered to minimize the adverse effects by galvanic corrosion, but the galvanic corrosion as well as the localized corrosion such as pitting or crevice corrosion can be occurred in Co-Cr alloy.

초내식성 스테인리스강에 HA 코팅층 형성을 위한 플라즈마 용사 공정의 Taguchi 실험 설계 연구

오근택,박용수 ( Keun Taek Oh,Yong Soo Park ) 한국부식방식학회 1997 Corrosion Science and Technology Vol.26 No.1

타이타늄 임플란트와 상부구조물의 갈바닉 쌍의 전기화학적 특성

오근택,김명화,최병갑,김경남 大韓齒科器材學會 2003 대한치과재료학회지 Vol.30 No.1

For the aesthetic and functional restoration of edentulous patients, recently dental implants have been used widely. Dental implants and restorative alloys are required with the high corrosion resistance. Suprastructure and implant with different compositions, which are in electrical contact, may develop galvanic or coupled corrosion problems. Besides galvanic corrosion, crevice and pitting corrosion may occur in the marginal gap or the gap between dental implant assemblies. In this study, Ti implants, gold, silver-palladium, cobalt-chromium and nickel-chromium suprastructures were used to investigate their galvanic and crevice corrosion of suprastructure/Ti implant couples. Potentiodynamic and potentiostaic testing were performed in artificial saliva at 37℃. Potentiodynamic testing was carried out at the potential scan rate of 1 ㎷/sec and in the range of -600∼1600 ㎷(SCE). Potentiostatic testing such as open circuit potential and current densities at -250, 0 and 250 ㎷(SCE) was performed for 5000 seconds in artificial saliva. After electrochemical testing, the surface and cross-sectional morphologies of the samples were observed using optical microscopy. Potentiodynamic test results indicated that suprastructure/Tim implant couples exhibited the passive current density range of 0.5∼12 ㎂/㎠, Ti abutment/Tim implant and gold/Tim implant couples exhibited relatively low passive current density, Co-Cr/Tim implant couples the highest. Co-Cr and Ni-Cr/Tim implant couples showed the breakdown potentials of 700 and 570 ㎷(SCE), respectively. Open circuit potentials of silver, Ti abutment, gold, Ni-Cr and Co-Cr/Ti implant couples were -93.2±93.9, -123.7±58.8, -140.0±80.6, -223.5±35.1, and -312.7±29.8, respectively and stable according to immersion time. The couples exhibited cathodic current densities at -250 ㎷(SCE), especially, gold and silver alloys showed the high cathodic current densities of ±3.18 and ±6.63 ㎂/㎠, respectively. At 250 ㎷(SCE), Ti abutment/Ti implant couples exhibited the lowest current density of 9.48×10^-2 ㎂/㎠, and gold, Ni-Cr, Co-Cr and silver/Ti implant couples exhibited 0.313, 1.27, 5.60 and 8.06 ㎂/㎠, respectively. The couples exhibited relatively low current densities at 0 ㎷(SCE). The photographs after electrochemical testing showed crevice or pitting corrosion in the marginal gap and suprastructure surface. Although Co-Cr/Ti implant couples among the tested samples had the possibility of the galvanic corrosion, its degree was not significant.

초내식성 스테인리스강 선재와 브라켓의 내식성 및 금속 이온 용출 특성

오근택,정경진,황충주,박용수,김경남 大韓齒科器材學會 2001 대한치과재료학회지 Vol.28 No.4

Metallic orthodontic appliances are known to release metal ions in an oral cavity. It is not advisable that toxic corrosion products derived from the appliances is absorbed into the body. Metal ions release from orthodontic appliances is known to have large effects on the result of orthodontic treatment and systemic health. Metal bracket and wire were made of super stainless steel(S32050) with high corrosion resistance. The corrosion resistance and ion release property of S32050 and conventionally used appliances were examined. Four types of wire were ligated in either super stainless steel(SB) or Tomy bracket(TB) with O-ring, and then each group was immersed in an artificial saliva at 37℃ for 12 weeks. Amount of released metal ions was measured with immersion time by graphite furnace atomic absorption spectroscopy and surface morphology was investigated. S32050 showed the low passive current density of about 1 μA/㎠ and the stable passive region to a high potential in artificial saliva. S32050 appliances did hardly release nickel ions in artificial saliva. S32050 wire(SRW) and NiTi wire(NW) didn't show significant difference of Ni ion release with immersion time, meanwhile, Remanium wire(RW) showed significant difference in 12 weeks. Ni ion releasce from the brackets didn't show any significant difference with immersion time and between SB and TB. Amounts of Ni ion released from TB-SRW showed significant difference in 12 weeks, those from TB-RW showed significant difference from 4 weeks later and highest release among all groupsin12weeks. TB-NW released little Ni ion for all immersion time and showed significant difference from 4 weeks later, TB-TW(TMA wire) showed significant difference in 12 weks. SB-SRW didn't show any significant difference and SB-RW signigicant difference in 12 weeks,but lower compared with TB group. SB-NW and SB-TW didn't show any significant difference. Corrosion products didn't be observed in mostly groups during the immersion time, except that in TB-RW, they were observed on the bracket surface between O-ring and wire from 8 weeks later. Super stainless steel wire had good corrosion resistance compared with stainless steel wire, and it is believed that it can be used as orthodontic material for bracket and wire.

교정용 스테인리스강 선재의 기계적 특성에 미치는 응력제거 열처리 조건의 영향

오근택,황충주,김경남 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.1

Heat treatment is applied to orthodontic wires in order to relieve the stress that results from cold working and the orthodontist's manipulations for making loops, helical springs and archforms. Conventionally, the wires are heat-treated for a few minutes at higher temperature in an ambient. In this study, 4 types of wires were heat-treated in an air, argon or vacuum environment, and were either cooled in a furnace or a water bath. Mechanical properties of the heat-treated wires were investigated. Stress relief heat treatment increased the microhardness, strength and Young's modulus of the orthodontic wires. The increased factions of microhardness, maximal strength, yield strength and Young's modulus of the orthodontic wires by the heat treatment were approximately 0.4∼22.9%, 2.9∼14.8%, 3.7∼14.4% and 2.5∼9.0%, respectively. Yield strength and microhardness of the heat-treated wires were significantly different with the cooling methods. Microhardness and yield strength of the water-cooled wires were lower than those of the furnace cooled wires. It was considered because thermal stress was introduced to the wire by the rapid cooling. Stress relief heat treatment in and ambient oxidized the surface of the wires, and mechanical properties and surface cleanness of the water-cooled wires were lower than those of the furnace-cooled wires. Conclusively, orthodontic wires have to be heat-treated in vacuum condition or inert gas environment after plastic deformation and to be cooled in the furnace, in order to inhibit surface oxidation, minimize the decrease of corrosion resistance and improve the mechanical properties.