스테인리스강 소결체를 이용한 치과용 임플란트 개발(Ⅰ) : 치과용 소결체의 제작과 물성을 중심으로 Fabrication and Physical Properties of Sintered Stainless Steel

최한철,고영무,모웅남 大韓齒科器材學會 2003 대한치과재료학회지 Vol.30 No.3

The first factor to decide the success of dental implantation is sufficient, osseointegration between implant fixture and its surrounding bone tissue. Thus many studies about this have been under actively. In recent, one of them is to increase the roughness of the surface of an implant fixture by treating the surface of an implant fixture in various ways, increase the contact area between an implant fixture and its surrounding bone tissue and so induce a sufficient osseointegration between them. The roughness of the surface on an implant fixture can be increased by coating the smooth surface of an implant fixture with hydroxyapatite or titanium particles or by treating the surface with acid. But these ways can cause the failure of implantation in the long run due to the separatation of coated particles from an implant fixture and sometime; can't attain the sufficient osseointegration because of emitting ion into the surrounding bone tissue. To develop dental implant materials, fabrication and physical properties of sintered stainless steel have studied using hardness tester, tensile tester, SEM, TEM, EPMA, EDX. Stainless steel compacts containing Cu (2-10 wt%) were prepared either by electroless Cu-plating method which result in the increased homogenization in alloying powder or by Cu-elemental powder addition method on the stainless steel powder Experimental investigation foucusing on mechanical property was performed for Cu-added samples to study the effects of Cu content, electroless Cu-plating method, and Cu-elemental powder addition method on the surface characteristics of sintered stainless steel in Mo and Cu in sintered stainless steel on the mechanical behaviors. Microstructural characterization revealed that Cu-addition by electroless Cu-plating method resulted in less porous material compared that prepared by Cu-elemental powder addition method. Since Cu is blown to be effective in reducing the precipitation of chromium carbide at sensitization temperature, Cr concentration in electroless Cu-plating method was uniformly distributed in the grain boundary and in the matrix. The sintered density in electroless Cu-plating method increased with reducing porosity as a result of the Cu-uniform distribution due to electroless Cu plating during the sintering process. The amount of Cu added in the sintered stainless steel affected significantly tensile strength which increased with 4 wt% Cu and decreased with more than 7 wt% Cu.

치과용 임플란트로 적용을 위한 스테인리스강 표면의 Ti/TiN film 증착

최한철,고영무,백대화,박영록,박지윤 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.1

A study on Ti/TiN film coating on stainless steels for application as dental implants have been investigated. The stainless steels containing Ti were solutionized 1050℃ for 1hr. Then the surface was deposited with Ti and TiN by using electron-beam deposition method. The deposited layer and microstructure were analyzed by using XRD, WDX, XPS and SEM. The hardness and wear resistance of deposited surface were examined and corrosion behavior were investigated by using potentiostat, XPS and SEM. The results were as follows: 1. Some defects showed on the deposited surface, such as crater and microdroplet, and surface roughness increased in all specimen after TiN deposition. 2. Ti/TiN deposited layer showed columnar structure which nucleated and grew on the special crystalline direction and plane: Ti/TiN layer TiN(220) and TiN(200). 3. The hardnesses of Ti/TiN layer was higher than that of TiN layer. 4. In case of stainless steel containing high Ti content, Ti/TiN layer showed better wear resistance than that of TiN layer. 5. Pitting potential of TiN film in NaCl solution increased as Ti content increased, but pitting potential of Ti/TiN film were not affected by the Ti content of substrate. Pitting potential of Ti/TiN film showed high value than that of TiN film in NaCl solution. The number and size of pits were apparently decreased by Ti/TiN film deposition on the stainless steel.

표면처리방법에 따른 강화된 치과용 임플란트의 개발 : Ⅰ.전자빔 진공증착법에 의한 치과용 임플란트의 내구성 개선 Ⅰ.Improvement of Endurance for Dental Implants by EB-PVD Coating Method

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

Ti-6Al-4V alloy has an excellent fatigue strength but it has a low corrosion resistance compared with pure titanium. To develop the alloys for the dental implant with better corrosion resistance, Ti, TiN and Ti/TiN were coated on Ti-6Al-4V alloy by electron-beam physical vapor deposition(EB-PVD) method. Ti-6Al-4V alloys were made under the condition of hydrogen and vacuum arc furnace and were quenched at 1,000℃ under high purity dried Ar gas atmosphere and were hold at 500℃ for 2hrs to achieve the fatigue strength(1140㎫) of alloys. Corrosion tests of three coated alloys were used to investigate the electrochemical corrosion behavior in 0.9% NaCl solution. The corrosion potential(+200㎷) of Ti-6Al-4V alloys coated with Ti/TiN is higher and lower active and passive current densities than that of alloys coated with Ti(-300㎷), TiN(-100㎷) and uncoated ones(-400㎷). Also uncoated alloys showed the decreasing of the pitting and repassivation potential in comparison with Ti, TiN and Ti/TiN coated alloys. The amount of Ti released was decreased in the order of Ti/TiN, TiN and Ti coated alloys. We conclude that coating Ti/TiN on Ti-6Al-4V is the most effective to improve of corrosion resistance of Ti-6Al-4V alloys with lower corrosion resistance to some extent by using Ti/TiN multilayer EB-PVD coating method.

치과용 자성 어태치먼트 재료의 안정성 개선에 관한 연구 : II.질화티타늄 코팅이 치과용 자성재의 내식성에 미치는 영향 Ⅱ.Effect of TiN Coating on Corrosion Resistance of Dental Magnetic Materials

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

Dental magnetic materials have been applied to removable prosthetic appliances, maxillofacial prostheses, obturator and dental implant 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 TiN and then electrochemical corrosion test were performed in 4 kinds of electrolyte solutions(0.9% NaCl. 1% lactic acid, 0.05% HCl and modified Fusayama's artificial saliva). From this study, corrosion behavior, 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. TiN layer coated on magnet grows into preferred direction with lamellar structure and its thickness is 3.0㎛. 2. Sm-Co base magnetic materials coated with TiN have good corrosion resistance in 1% lactic acid and their pitting corrosion can not be seen. 3. Nd-Fe-B base magnetic materials coated with TiN showed good tendency of corrosion resistance in 0.05% HCl solution. 4. The amount of elements released from both Sm-Co and Nd-Fe-B base magnetic materials coated with TiN were more significantly decreased than that of uncoated magnetic materials. 5. The mean surface roughness values of both Sm-Co and Nd-Fe-B base magnetic materials coated with TiN were smooth than that of uncoated magnetic materials after corrosion test. 6. The decreasing rate of microhardness of both Sm-Co and Nd-Fe-B base magnetic materials coated with TiN were lower than that of uncoated magnetic materials after corrosion test. 7. Dental magnetic materials coated with TiN produced various corrosion products such as TiO, TiO₂, Ti₂O₃on the surface and resulted in better corrosion resistance than uncoated magnetic materials. In conclusion, it is considered that the corrosion problem of dental magnetic materials could be solved to some extent by EB-PVD with TiN on the surface of dental magnetic materials.

황색포도구균의 균혈증에서 초기 항생제 치료가 예후에 미치는 영향

김성한,박완범,이기덕,강철인,최영주,김홍빈,박상원,김의석,오명돈,김의종,최강원 대한감염학회 2002 감염 Vol.34 No.5

광범위 베타 락탐계 항생제 분해 효소를 생성하는 폐렴간균에 의한 균혈증이 발생한 환자에서 감영의 위험 인자 및 치료 결과

강철인,김성한,방지환,김홍빈,박상원,최영주,오명돈,김의종,최강원 대한감염학회 2003 감염과 화학요법 Vol.35 No.2

목적 : 본 연구는 ESBL을 생성하는 K. pneumoniae에 의한 균혈증 환자에서 감염의 위험 인자 및 치료 결과를 알아보고자 시행하였다. 방법 : 1998년 1월부터 2002년 4월까지 혈액 배양 검사에서 동정된 K. pneumoniae를 대상으로 NCCLS guidelines과 이중 디스크 확산법(double-disk diffusion test)을 이용하여 ESBL 생성 여부를 확인하였다. ESBL 생성 균주에 의한 균혈증 환자 60명(환자군)에 대해 ESBL을 생성하지 않는 균주에 의한 균혈증 환자들(대조군)을 연령, 성별, 균혈증 발생 시점을 고려하여 1:2 또는 1:3으로 배정하였다. 총 159명의 대조군을 선정하였고 후향적인 환자-대조군 연구를 시행하였다. 결과 : 환자군과 대조군 사이에 연령, 성별, APACHE Ⅱ score, 주된 감염 부위의 유의한 차이는 없었다. ESBL을 생성하는 K. pneumoniae에 의한 균혈증이 발생할 독립적인 위험 인자에는 요관 삽입, 균혈증 발생 이전 72시간 동안 침습적인 시술을 받은 경우, 균혈증 발생 이전 30일 동안 투여받은 항생제 개수가 있었다. 초기 항생제 치료 72시간 후의 반응을 평가하였을 때, 완전 반응(complete response)은 대조군에서 더 많았고(13.3% vs. 40.3%, P<0.001), 치료 실패(treatment failure)는 환자군에서 더 많았다(33.3% vs. 11.9%, P<0.001). 7일 사망률은 환자군에서 20% (12/60), 대조군에서 15.6% (25/159)이었고(P=0.451), 30일 사망률은 환자군에서 30% (18/60), 대조군에서 24.5% (39/159)이었다(P=0.410). ESBL 생성 균주에 의한 균혈증이 있는 환자들에서 최종 항생제 치료가 부적절했던 환자들을 제외하고 30일 사망률을 분석하였을 때 효과적인 항생제 치료의 지연은 사망률을 높이지 않았다(11.1% vs. 9.1%, P=1.000). 결론 : ESBL을 생성하는 K. pneumoniae에 의한 균혈증이 있는 환자에서 초기 항균제 치료 72시간 후의 치료 반응률은 낮지만 사망률은 유의하게 증가하지 않았다. 원인균이 동정된 후 최종 치료 항생제의 선정이 적절하다면 초기에 효과적인 항생제 투여의 지연은 사망률을 유의하게 증가시키지는 않았다. Background : This study was conducted to evaluate risk factors for infection and treatment outcome of bloodstream infection due to extended spectrum β-lactamases(ESBL)-producing K. pneumoniae. Methods: ESBL production was evaluated by NCCLS guidelines and/or double-disk synergy test in K. pneumoniae blood isolates stored from January, 1998 to April, 2002. Sixty patients with bloodstream infection due to ESBL-producing K. pneumoniae (case patients) were compared with 159 matched control patients with bloodstream infection of non-ESBL-producing K. pneumoniae. Retrospective case-control study was performed. Results : There were no significant differences in age, sex, APACHE Ⅱ score, and the primary site of infection between the case and control groups. In multivariate analysis, significant independent risk factors associated with bloodstream infection due to ESBL-producing K. pneumoniae were urinary catheterization, invasive procedure within previous 72 hours, and the number of antibiotics administered within previous 30 days. In clinical response at 72 hours after initial antibiotic treatment, complete response rate was higher in the controls (13.3% vs. 40.3%, respectively, P<0.001), however, treatment failure rate was higher in the cases (33.3% vs. 11.9%, respectively, P<0.001). Overall 7-day mortality rates in the cases and the controls were was 20% (12/60) and 15.7% (25/159) (P=0.451), respectively, and overall 30-day mortality rates were 30% (18/60) and 24.5% (39/159), respectively (P=0.410). When the patients with bloodstream infection of ESBL-producing organism were evaluated and the patients who received inadequate definitive antibiotic treatment were excluded, delayed effective antibiotic treatment was found to be not associated with higher mortality. Conclusion : In patients infected with ESBL-producing K. pneumoniae bacteremia, clinical response rate at 72 hours after antimicrobial therapy was lower, but the increase of mortality rate was not significant. Delayed effective antibiotic treatment was not associated with higher mortality, when definitive appropriate antibiotic treatment was prescribed.

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.

전자빔 진공증착을 이용한 치과용 임플란트재의 표면 전처리법에 따른 HA 코딩효과

고영무,최한철,최낙찬 大韓齒科器材學會 2002 대한치과재료학회지 Vol.29 No.4

The dental implant materials require good mechanical properties, such as fatigue strength, combined with a high resistance to corrosion. For increasing fatigue resistance and delaying onset of stress corrosion cracking, shot-peening has been used for over 50 years to extend service life of metal components, However, there is no information on the electrochemical behavior of shot-peened and hydroxyapatite(HA) coated Ti-6Al-4V alloys. To increase fatigue strength, good corrosion resistance, and biocompatibility, the electrochemical characteristics of Ti/TiN/HA coated and shot-peened Ti-6Al-4V alloys by EB-PVD have been researched by various electrochemical method in 0.9%NaCl The coated layer and surface showed the formation of dense and uniform surface in the case of TiN/HA and Ti/TiN/HA film coated samples. The hardness of shot-peened Ti-6Al-4V alloys(SPA) increased as SP treatment time increased. Electrochemical measurements showed that, in the case of shot-peened Ti-6Al-4V alloys, the corrosion and pitting potential increased due to the SP induced removal of defects, such as inclusion, scratch, and pore on the surface, whereas passivation and active current density decreased as the SP time increased. For the HA coated samples, pitting and repassivation potential increased in the order of Ti/TiN/Ha > TiN/HA > Ti/HA > HA coated SPA. Results suggest that the best pitting corrosion behavior is shown by Ti/TiN/HA coated SPA with a fatigue strength and biocompatibility.

치과 자석 어태치먼트 재료에 적용을 위한 이온질화된 Ti 첨가 스테인리스강의 표면특성

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

Dental magnetic attachment have been applied to removable prosthetic appliances, maxillofacial prostheses, obturator and dental implant but they still have some problems such as low corrosion resistance in oral environments. To increase the corrosion resistance of dental magnetic materials. Nd-Fe-B materials were sealed with stainless steel, but pitting corrosion, intergranular corrosion and erosion corrosion occurred predominantly at welded zone and center of magnetic attachment in corrosive environment and mechanical wear condition. In order to develop corrosion resistance of magnetic materials, the surface modification of stainless steel for magnetic attachment sealing materials were investigated by utilizing potentiostat. It was found that plasma nitriding at 380℃, compared with 500℃, produced a good corrosion resistance as nitriding time increased, whereas stainless steel containing low Ti content showed that pitting potential and corrosion potential decreased.