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標題: | 電化學系統之電阻抗研究:根管治療與雙金屬薄膜腐蝕 Impedance Study of the Electrochemical Systems:Endodontic Treatment and Bimetallic Thin-Film Corrosion |
作者: | Jui-Hsiung Huang 黃瑞雄 |
指導教授: | 顏溪成 |
關鍵字: | 根管治療,根尖指標,電化學阻抗頻譜, endodontic treatment,apex indication,electrochemical impedance spectroscopy, |
出版年 : | 2007 |
學位: | 博士 |
摘要: | 本論文研究主要涉及有關二種電化學系統-根管治療與雙金屬薄膜腐蝕。第二、三章探討有關牙科根管治療之電阻抗應用,對於此非法拉第阻抗系統而言,根管中溶液導電度與根管幾何形狀是影響電阻抗偵測牙齒根尖的二項重要因素,因此第二、三章即分別針對此二大因素進行深入探討;第四章則是探究有關鉬/鋁雙層金屬薄膜於溶液中之電化學特性及法拉第程序。
目前電子根尖定位器雖已廣泛應用於牙醫治療,然而此根管系統的電阻抗特性卻亟需進一步探究,論文中針對牙齒根管進行生物體外電阻抗分析實驗,並藉由此結果建構牙齒系統複雜結構之等效電路模型,經由此部分研究發現,相較於其他研究者過去所提出的電路模型,此論文所提出的新穎等效電路模型,與實驗結果最為吻合,且體外電阻抗試驗現象與根管中導電溶液效應,亦可藉由此新等效電路模型,得到合理地解釋與清楚瞭解。經由生物體外電阻抗實驗分析發現,除了著名的阻抗比值根尖指標之外,此論文所提出的比值變異法(SQ)根尖指標,亦具有消除根管中溶液導電度因素之功能,當探測電極到達根尖點或超過根尖點時,比值變異數值將會低於0.05,而根管中的阻抗行為亦能由修飾型阻抗比值(Q)進一步被瞭解。另外藉由本論文所建立的根管系統理論電路分析,亦發現阻抗比值的確具有消除導電度效應之功用。 對於根管治療而言,根尖孔大小是目前嚴重影響電子根尖定位器精準度的一項重要因素,特別是對於缺乏狹縮的開放性根尖孔而言。在論文此部分實驗發現,體外電阻抗大小會隨著根尖孔直徑增大而變小,且探測電極移動時阻抗比值之變化幅度,會隨著根尖孔直徑增大而遽減,此現象推斷為阻抗比值法在臨床應用上,對較大根尖孔直徑的根管難以準確指示其根尖孔位置之主因。為了克服此干擾因素,本論文提出一個基於三頻量測的創新根尖指標-容抗基礎之阻抗修正,且經由體外電阻抗實驗模擬發現此創新指標能將根尖孔大小因素予以去除。對於根尖孔大小理論分析方面,基於電化學盤電極與幾何狹縮電阻的理論,根尖孔狹縮程度的理論模型亦進一步被建立,經由理論模型之模擬結果顯示,阻抗比值法確實會嚴重受到根尖孔狹縮程程度與根尖孔大小所影響,反之本論文所提出的電抗基礎阻抗修正法則與之無關,此模型模擬結果與體外電阻抗試驗結果趨勢相當一致。本論文的研究結果將有助於進一步瞭解牙齒根管系統之複雜電性機制,且對於根尖定位器在臨床牙醫應用上預料將有極大裨益。 鉬/鋁雙層金屬薄膜結構目前已廣泛應用於薄膜電晶體液晶顯示器的金屬導線,然而實驗發現,此雙層薄膜浸置於氫氧化四甲銨溶液中五分鐘後,導線表面將會出現污點瑕疵,藉由探究雙層金屬薄膜與溶液界面的電化學特性行為與各種表面分析,推斷應是底層鋁金屬的表面特性對於沈積溫度十分敏感,因此造成高溫沈積下的鋁金屬薄膜,難以被鉬金屬薄膜所完全覆蓋,當電化學活性較高的鋁金屬少部分暴露於溶液時,將進一步誘發局部賈凡尼腐蝕,研究發現降低薄膜沈積溫度與增加鉬金屬覆蓋厚度,均能有效抑制污點瑕疵的發生,此部分結果對於瞭解雙層金屬薄膜之腐蝕行為及金屬導線之沈積品質將會有所助益。 The electrochemical systems concerning endodontic treatment and bimetallic thin-film corrosion have been investigated in this study. Chapters 2 and 3 mainly deal with electrochemical impedance with nonfaradaic process for endodontic treatment. Two important cell-factors about electrolytic conductivity and geometry of the simulated canal system have been considered for impedance distribution of this dental system. The electrochemical characteristics and faradaic process of Mo/Al double thin-film in solution have also been investigated in this study and described in chapter 4. Electronic apex locators (EALs) have been widely used in the dental treatment, and it is important to study the impedance characteristics of the root canal system. The study of impedance characteristics of the endodontic treatment with various electrolytes have been described in chapter 2, in which the in-vitro impedance measurements of root canals were performed and then used for the build-up of lumped equivalent-circuit model to the complicated anatomy of human tooth. The new proposed equivalent-circuit model fits the experimental results well compared with other models proposed previously by other researchers. Based on this new proposed equivalent-circuit model, the experimental results can be explained reasonably and the effect of electrolytes filling the canal is clearly understood. In addition to well-known index of impedance quotient in the literature, it has been found that the variation ratio method, SQ, can be employed as a significant indication of apex position, in which it can overcome the interference of electrolyte in canals more effectively. The values of variation ratios are below 0.05 at the apex and over-apex region for any electrolyte in the canal. Various impedance behaviors could be figured out from values of modified impedance quotient, Q. Furthermore, a typical theoretical model has also been set up for the root canal system to help explain the electric mechanism of root canal. It has shown that the principle of impedance quotient is valid for the elimination of electrolytic effect. The apical size, especially for wide-open apex is now a crucial effect hampering the precision of EALs. As described in chapter 3, it has been found from in-vitro experiments that total impedance of the canal system decreased with enlarged apical diameter. The gradient change in impedance quotient would be less sharp with enlarged apical diameter, which may result in the inaccurate measurement of apex position to be obtained. Accordingly, the impedance quotient is not good enough to offer a good indication of apical endpoint for larger apical size. To overcome this apex size effect for the application of EAL, a novel apex indication, capacitance-base impedance correction, has been proposed based on three frequency measurements. By the in-vitro experiments of blocks and extracted teeth, it has been found that it is valid for the capacitance-base impedance correction for eliminating the apical size effect. For theoretical analysis, the model of a constrictive system with semi-infinite medium, which simulated the anatomy of tooth, has been proposed based on the electric behaviors of the disk electrode and geometrically constrictive resistance. From the simulated results, it indicated that the impedance quotient would be seriously restricted by apical constriction or size, whereas the capacitance-base impedance correction number was independent of that. The simulation results are in good agreement with that of in-vitro experiments. It would be helpful to understand the complicated mechanism of the human canal system as well as to improve the accuracy of the clinically dental applications. The double thin-film structure of molybdenum (Mo) over aluminum-neodymium (Al-Nd) alloy is widely used for gate-metal lines in thin-film transistor liquid crystal displays (TFT-LCD). The electrochemical characteristics of the two-layer films/electrolyte interface in alkaline TMAH solution have been investigated using electrochemical measurement and surface analytical techniques. From the experimental results, it can be deduced that the surface topography of the Al-Nd layer is sensitive to deposition temperature. The Al-Nd layer that deposited at higher temperature was difficult to be covered completely by the Mo-capped layer. Some Al active regions are exposed to alkaline TMAH solutions, and more galvanic local corrosion is induced. Lowering film-deposition temperature and covering Mo layer sufficiently have been considered to be quite effective for avoiding blemishes, as found in this study. It will be helpful to understand the corrosion behavior of double thin-film and improve the quality of metal line deposition. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/25016 |
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