目前製作牙科金屬補綴物仍然是以包埋鑄造的方式進行製作，然而此方法對於較大型的牙科金屬補綴物容易產生因為收縮膨脹而導致變形的情形發生。另外，當牙科金屬補綴物在置入病人口腔中之後也會因為病人進行清潔工作而將義齒取出及戴入的過程中，以及日常生活進食的咀嚼而產生應力，導致牙科金屬補綴物較脆弱的結構部份容易發生疲勞破壞而需要進行雷射焊接修補的情形發生。
目前一些口腔保健用品大多含有氟，而有研究報告指出氟離子容易對鈦金屬造成腐蝕，因此本研究是探討經由 Nd:YAG 雷射焊接後的Ti-6Al-7Nb合金於模擬口腔環境下之疲勞性質。Ti-6Al-7Nb合金經鑄造後分別以310 V、330 V及350 V的焊接電壓 ( 相當於焊接能量11 J、14 J及17 J ) 進行Nd:YAG雷射焊接，再於空氣中、不含氟之人工唾液及含有0.5%NaF之人工唾液中進行疲勞試驗。實驗結果顯示，增加Nd:YAG雷射焊接能量可提高鑄造Ti-6Al-7Nb合金焊接連接體的疲勞壽命；鑄造Ti-6Al-7Nb合金焊接連接體在空氣中的疲勞壽命明顯高於在人工唾液中以及含氟人工唾液中之值，然而在人工唾液環境中試驗之疲勞壽命與含氟人工唾液環境中試驗之疲勞壽命兩者之間並沒有顯著性的差異。

The denture prosthesis was still made by Investment Casting technique at present time. But this method had problems such as shrinkage and expansion which may result in deformation of the castings, especially for some large sized prosthesis.
Meanwhile, fatigue fracture of denture prosthesis may take place due to stress after repeated insertion and removal as for clean up or under mastication. To fix the prosthetic fracture, laser-welding is recommended for Ti alloys.

This study was to investigate the fatigue property of Nd : YAG laser-welded Ti-6Al-7Nb alloys in artificial saliva. Commercial cast Ti-6Al-7Nb alloy joints were proceeded to Nd:YAG laser welding (welding voltage: 310, 330, 350 V equivalent to energy: 11, 14, 17 J) for fatigue test. According to the present studies, fluoride ions may induce the corrosion of Ti joints. As most OTC oral hygiene products containing fluoride ions, besides in air and artificial saliva, the fatigue lives of Ti-6Al-7Nb joints were also evaluated in fluoride-containing (0.5% NaF) artificial saliva.
The results showed that increasing Nd:YAG laser welding energy would increase the fatigue life of Ti-6Al-7Nb alloy; the average fatigue life of laser-welded Ti-6Al-7Nb alloy joints in air environment was higher than that obtained in both artificial saliva groups (with and without fluoride). And there was no significant difference between the fluoride-containing group and artificial saliva (without fluoride) group for fatigue life.

總目錄
中文摘要 I
英文摘要 II
總目錄 III
表目錄 V
圖目錄 VI
第一章 緒論 1
1.1. 前言 1
1.2. 目的 7
第二章 材料與方法 8
2.1. 試片準備 8
2.1.1. 包埋去蠟 8
2.1.2. 鑄造 8
2.1.3. 試片處理 9
2.1.4. 雷射焊接 9
2.2. 疲勞性質測試 10
2.2.1. 人工唾液製備 10
2.2.2. 疲勞試驗 10
2.3. 表面觀察及分析 11
2.3.1. 掃描式電子顯微鏡觀察 11
2.3.2. 影像分析軟體分析 11
2.3.3. 統計分析 12
第三章 結果 13
3.1. 焊接連接體疲勞壽命 13
3.2. 焊道熔融面積 13
3.3. 疲勞破斷類型 14
3.4. 掃描式電子顯微鏡觀察 14
第四章 討論 16
第五章 結論 18
第六章 參考文獻 19
表目錄
表2-1 改良式 Fusayama 人工唾液 24
表3-1 焊接連接體疲勞壽命 ( cycles ) 25
表3-2 破斷面焊道熔融面積 26
表3-3 疲勞破斷類型 27
圖目錄
圖2-1 本研究之實驗流程圖 28
圖2-2 壓克力塑膠試片植立於鑄道圓錐台 29
圖2-3 鈦金屬專用氧化鎂系包埋材 30
圖2-4 加熱去蠟爐 31
圖2-5 升溫加熱之去蠟流程圖 32
圖2-6 離心真空加壓純鈦鑄造機 33
圖2-7 噴砂機 34
圖2-8 快速切割機 35
圖2-9 超音波洗淨機 36
圖2-10 焊接用傾斜 20o 特製金屬平台 37
圖2-11 雷射焊接機 38
圖2-12 焊點二分之一覆蓋 39
圖2-13 雷射焊接參數對照能量圖 40
圖2-14 頓動態疲勞試驗機 41
圖2-15 水溶液裝置示意圖 42
圖2-16 掃描式電子顯微鏡 43
圖3-1 以掃描式電子顯微鏡觀察不同焊接能量之Ti-6Al-7Nb焊接連接體於空氣環境中進行疲勞試驗後之破斷面
44
圖3-2 以掃描式電子顯微鏡觀察不同焊接能量之Ti-6Al-7Nb焊接連接體於不含氟人工唾液中進行疲勞試驗後之破斷面
45 & nbsp;
圖3-3 以掃描式電子顯微鏡觀察不同焊接能量之Ti-6Al-7Nb焊接連接體於含有0.5%NaF人工唾液中進行疲勞試驗後之破斷面
46
圖3-4 以掃描式電子顯微鏡觀察焊接能量14 J之Ti-6Al-7Nb焊接連接體於三種不同環境中進行疲勞試驗後之焊道區域破斷面。
47
圖3-5 以掃描式電子顯微鏡觀察焊接能量17 J之Ti-6Al-7Nb焊接連接體於三種不同環境中進行疲勞試驗後之焊道區域破斷面
48
圖3-6 焊接連接體疲勞壽命 ( cycles ) 49

Au A.R., Lechner S.K., Thomas C.J., Mori T., Chung P.,
Titanium for removable partial dentures (III): 2-year clinical follow-up in an undergraduate programme., J Oral Rehabil 2000;27(11):979-985.

Albrektsson T. Bone–metal interface in osseointegration. J Prosthet Dent 1987;57:597-607.

Boyer R, Welsch G, Collings EW. Titanium alloys. Materials Park, OH: ASM International, 1994. p. 224-227.

Baba N., Watanabe I., Penetration depth into dental casting alloys by Nd:YAG laser., J Biomed Mater Res B Appl Biomater 2005;72(1):64-68.

Chai T, Chou CK. Mechanical properties of laser-welded cast titanium joints under different conditions. J Prosthet Dent 1998;79:477-483

Chai T., Chou C.K., Mechanical properties of laser-welded cast titanium joints under different conditions., J Prosthet Dent 1998;79(4):477-483.

Davidson JA, Mishra AK, Kovacs P, Poggie RA. New surfacehardened, low-modulus, corrosion-resistant Ti-13Nb-13Zr alloy for total hip arthroplasty. Bio-Med Mater Eng 1994;4:231-243.

Doi H, Wang TJ, Nakano T, Kobayashi I, Yoneyama T, Hamanaka H. Ion release from Ti-6Al-7Nb alloy dental castings in 1.0% lactic acid. J Soc Dent Mater Dev 1997;16:182-186.

Guyuron B. and Lasa CI. Jr., Reaction to stainless steel wire following orthognathic surgery., Adv Plast Reconstr Surg 1992;89:540-542.

Hhruska AR, Borelli P. Quality criteria for pure titanium casting, laboratory soldering,intraoral welding, and a device to and in making uncontaminated castings. J Prosthet Dent 1991;66:561-565.

Huang H.H., Chiu Y.H., Lee T.H., Wu S.c., Yang H.W., Su K.H.,and Hsu C.C., Ion reslease form NiTi orthodontic wires in artificial saliva with various acidities., Biomaterials 2003;24:3585-3592.

Johansson CB, Albrektsson T. A removal torque and histomorphometric study of commercially pure niobium and titanium implants in rabbit bone. Clin Oral Implants Res 1991;2:24 -29.

Kobayashi I, Doi H, Takahashi M, Nakano T, Yoneyama T, Hamanaka H. Castability and mechanical properties of Ti-6Al- 7Nb alloy dental-cast. J Soc Dent Mater Dev 1995;14:406-413.

Kitahara K., Kubo F., Takahashi J., Thermal expansion typed investments for casting titanium., Dent Mater J 2000;23(1):1-7.

Lugowski SJ, Smith DC, McHugh AD, Loon V. Release of metal ions from dental implant materials in vivo: Determination of A1, Co, Cr, Mo, Ni, V and Ti in organ tissue. J Biomed Mater Res 1991; 25:1443-1458.

Lee Y.T., Welsch G.E., Young''s modulus and damping of Ti-6Al-4V alloy as a function of heat treatment and oxygen concentration., Mater Sci Eng 1990;128(1):77-89.

Liu J, Watanabe I, Yoshida K, Atsuta M. Joint strength of laster-welded titanium. Dent Mater 2001;18:143-148.

Lucas L.C., Lemons J.E., Biodegradation of restorative metallic systems., Adv Dent Res 1992;6:32-37.

Nakagawa M., Matsuya S., Shiraishi T., and Ohat M., Effect of fluoride concentration and Ph on corrosion behavior of titanium for dental use., J Dent Res 1999;78:1568-1572

Neo T.K., Chia J., Gilbert J.L., Wozniak W.T., Engelman M.J.,Mechanical properties of titanium connectors., J Prosthodont
1996;9:379-393.

O’Brien WJ. Dental materials and their selection. Chicago, IL: Quintessence Publishing Co., Inc.; 2002. p. 372-377.

Ohkubo C, Shimura I, Aoki T, Hanatani S, Hosoi T, Okabe T. In vitro wear assessment of titanium alloy teeth. J Prothodont 2002;11:263-269.

Okazaki Y, Iro Y, Iro A, Tateishi T. Development of new titanium alloys for medical implants (I): Microstructure and mechanical properties. Mech Eng Lab Rep 1992;46:397-416.

Rafael Del Castillo, Ercoli Carlo, Graser Gerald N., Tallents Ross H., and Moss Mark E., Effect of ring liner and casting ring temperature on the dimension of cast posts., J Prosthet Dent 2000;84(1):32-37.

Semlitsch MF, Weber H, Streicher RM, Schon R.Joint replacement components made of not- forged and surface-treated Ti- 6Al-7Nb alloy., Biomaterial 1992;13:781-788.

Suzuki Y., Ohkubo C., Abe M., and Hosoi T., Titanium removable partial denture clasp repair using laser welding: A clinical report., J Prosthet Dent 2004;91(5):418-420.

Schiff N., Grosgogeat B., Lissac M., and Dalard F., Influence of fluoride content and pH on the corrosion resistance of titanium and its alloys., Biomaterials 2002;23:1995-2002.

Taylo J.C.r, Hondrum S.O., Prasad A., Brodersen C.A., Effects of joint configuration for the arc welding of cast Ti-6Al-4V alloy rods in argon., J Prosthet Dent 1998;79(3):291-297.

Vallittu P.K., Kokkonen M., Deflection fatigue of cobalt-chromium, titanium, and gold alloy cast denture clasp., J Prosthet Dent 1995;74(4):412-419.

Woodman IL, Jacobs IJ, Galante JO, Urban RM. Metal ion release from titanium-based prosthetic segmental replacements of long bones in baboons: A long-term study. J Orthop Res 1984;1:421.

Wiskott H.W.A., Doumas T., Scherrer S.S., Susz C., Belser U.C., Microstructures of brazings and welds using grade 2 commercially pure titanium., Int J Prosthodont 2001;14(1):40-47.

Wiskott H.W.A., Doumas T., Scherrer S. S., Susz C., Belser U. C., Mechanical and structural characteristics of commercially pure grade 2 Ti welds and solder joints., J Mater Sci Mater In Med 2001;55:719-725.

Zavanelli R.A., Pessanna Henriques G.E., Ferreira I., Corrosion-fatigue life of commercially pure titanium and Ti-6Al-4V alloys in different storage environments., J Prosthet Dent 2000;84(3):274-279.

楊弘華, 包埋材快速加熱下純鈦及鎳鉻合金鑄造物之機械性質，中山醫學大學口腔材料科學研究所碩士論文, 2005.

吳品姿, 純鈦金屬雷射熔接點在腐蝕環境下疲勞性質之研究，中山醫學大學口腔材料科學研究所碩士論文, 2004.