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Die Spacer가 도포된 보철용 크라운과 어버트먼트의 계면현상
박근형(K.H. Park),최한철(H.C. Choe) 한국표면공학회 2007 한국표면공학회지 Vol.40 No.4
Fit of a restoration and its cementation procedure is crucial to both its short and long term prognosis. Marginal fit is affected by many variables during the fabrication process. These variables, being intrinsic properties of the materials or the clinical technique used, can cause changes in the size and shape of the definitive restoration. Even if all variables are controlled carefully, the seating of a restoration can still be affected due to insufficient space for the luting agent. The use of die spacer can reduce the elevation of a cast restoration of a prepared tooth, decreased seating time, improve the outflow of excess cement, and lower the seating forces. The purpose of this study was to evaluate the marginal fidelity according to die spacer application times and measurement site. Casting alloys were prepared and fabricated using non-precious metal at 950℃. Specimens are divided into four groups: Ⅰ(die spacer painted casting for wax pattern), Ⅱ(die spacer non painted casting for wax pattern). The specimens were cut and polished for marginal gap observation. The marginal gap was observed using scanning electron microscopy (SEM).
보철용 지르코니아 어버트먼트의 표면적합도와 전기화학적 거동
박근형(K.H. Park),정용훈(Y.H. Jeong),김원기(W.G. Kim),최한철(H.C. Choe),김명수(M.S. Kim) 한국표면공학회 2009 한국표면공학회지 Vol.42 No.1
The fit between dental implant fixture and zirconia abutment is affected by many variables during the fabrication process by CAD/CAM program and milling working. The purpose of this study was to evaluate the surface compatibility and electrochemical behaviors of zirconia abutment for prosthodontics. Zirconia abutments were prepared and fabricated using zirconia block and milling machine. For stabilization of zirconia abutments, sintering was carried out at 1500℉ for 7 hrs. The specimens were cut and polished for gap observation. The gap between dental implant fixture and zirconia abutment was observed using field-emission scanning electron microscopy (FE-SEM). The hardness and corrosion resistance of zirconia abutments were observed with vickers hardness tester and potentiostat. The gap between dental implant fixture and zirconia abutment was 5~12 ㎛ for small gap, and 40~60 ㎛ for large gap. The hardness of zirconia surface was 1275.5 Hv and showed micro-machined scratch on the surface. The corrosion potentials of zirconia abutment/fixture was ?290 ㎷ and metal abutment/fixture was ?280 ㎷, whereas |Epit?Ecorr| of zirconia abutment/fixture (172 ㎷) was higher than that of metal abutment/fixture (150 ㎷). The corrosion morphology of metal abutment/fixture showed the many pit on the surface in compared with zirconia abutment/fixture.
다양한 유사체액과 인공타액에서 치과용 임플란트의 전기화학적 특성
김태한(T. H. Kim),박근형(G. H. Park),손미경(M. K. Son),김원기(W. G. Kim),장승현(S. H. Jang),최한철(H. C. Choe) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.5
Titanium and its alloy have been widely used in dental implant and orthopedic prostheses. Electrochemical characteristics of dental implant in the various simulated body fluids have been researched by using electrochemical methods. Ti-6Al-4V alloy implant was used for corrosion test in 0.9% NaCl, artificial saliva and simulated body fluids. The surface morphology was observed using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). The electrochemical stability was investigated using potentiosat (EG&G Co, 263A). The corrosion surface was observed using scanning electron microscopy (SEM). From the results of potentiodynamic test in various solution, the current density of implant tested in SBF and AS solution was lower than that of implant tested in 0.9% NaCl solution. From the results of passive film stability test, the variation of current density at constant 250 mV showed the consistent with time in the case of implant tested in SBF and AS solution, whereas, the current density at constant 250mV in the case of implant tested in 0.9% NaCl solution showed higher compared to SBF and AS solution as time increased. From the results of cyclic potentiodynamic test, the pitting potential and |Epit ? Ecorr| of implant tested in SBF and AS solution were higher than those of implant tested in 0.9% NaCl solution.
Ti-30Ta-(3~15)Nb 합금에 HA/Ti 복합 코팅한 표면의 교류임피던스 특성
정용훈(Y. H. Jeong),이호종(H. J. Lee),문영필(Y. P. Moon),박근형(G. H. Park),장승현(S. H. Jang),손미경(M. K. Son),최한철(H. C. Choe) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.5
A.C. impedance properties of HA/Ti compound layer coated Ti-30Ta-(3~15)Nb alloys have been studied by electrochemical method. Ti-30Ta binary alloys contained 3, 7, 10 and 15 wt% Nb were manufactured by the vacuum furnace system. And then specimen was homogenized at 1000℃ for 24 hrs. The sample was cut and polished for corrosion test and coating. It was coated with HA/Ti compound layer by magnetron sputter. The non-coated and coated morphology of Ti alloy were analyzed by X-ray diffractometer (XRD), energy X-ray dispersive spectroscopy (EDX) and filed emission scanning electron microscope (FE-SEM). The corrosion behaviors were investigated using A.C. impedance test (PARSTAT 2273, USA) in 0.9% NaCl solution at 36.5±1℃. Ti-30Ta-(3~15 wt%)Nb alloys showed the α+β phase, and β phase peak was predominantly appeared in the case of increasingly Nb contents. The microstructures of Ti alloy were transformed from needle-like structure to equiaxed structure as Nb content increased. From the analysis of coating surface, HA/Ti composite surface uniformed coating layer with 750 ㎚ thickness. The growth directions of film were (211), (112), (300) and (202) for HA/Ti composite coating on the surface after heat treatment at 550oC, whereas, the growth direction of film was (110) for Ti coating. The polarization resistance (Rp) of HA/Ti composite coated Ti-alloys were higher than those of the Ti and HA coated samples in 0.9% NaCl solution at 36.5±1℃. Especially, corrosion resistance of Ti-Ta-Nb system increased as Nb content increased.
박장현(J.H.Park),박근형(K.H.Park),임근철(K.C.Lim) 한국차학회 2001 한국차학회지 Vol.7 No.2
At harvesting tea plant leaf, moisture of tea leaves was 79.5%, and percentage of banjhi shoot to the total was 77.8%, and weight of 100buds was 29.41g. Rate of manufacture goods by Okro tea was increased because of slight powder and mass after made tea by 100℃ at 20 second steaming plus primary drying treated during 60min, at 80℃. Steaming treatment 20 second at 100℃ plus primary drying treated 60 min, at 80℃ and steaming treated 30 second at 100℃ plus primary drying treated 50 min, at 90℃ was higher contents of total nitrogen, total amino acid and chlorophyll than those of other treatment, but content of tanning was lower than in the other treatment. Consequently, these results meant that 100℃ 20second + 80℃ 60 min, treatment was considered to by the best streaming and primary drying tea rolling condition.
ZrN 및 TiN 코팅된 치과교정 용 미니나사의 표면특성과 전기화학적 거동
김신영(S. Y. Kim),문영필(Y. P. Moon),박근형(G. H. Park),조호형(H. H. Jo),김원기(W. G. Kim),손미경(M. K. Son),최한철(H. C. Choe) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.5
The dental orthodontic mini-screw requires good mechanical properties and high corrosion resistance for implantation in the bone. The purpose of this study was to investigate the electrochemical characteristics of TiN and ZrN coated orthodontic mini-screws, mini-screws were used for experiment. Ion plating was carried out for mini-screw using Ti and Zr coating materials with nitrogen gas. Ion plated surface of each specimen w as o bserved with f ield emission scanning e lectron microscopy ( FE-SEM), e nergy dispersive x -ray spectroscopy (EDX), and electrochemical tester. The surface of TiN and ZrN coated mini-screw were more smooth than that of other kinds of non-coated mini-screw due to dercrease of machined defects. The corrosion current density of the TiN and ZrN coated mini-screw decreased compared to non-coated sample. The corrosion potential of TiN and ZrN coated mini-screw were higher than that of non-coated mini-screw in 0.9% NaCl solution. The pitting corrosion resistance increased in the order of ZrN coated, TiN coated and non-coated wire. Pitting potential of ZrN coated mini-screw was the highest in the other specimens.