近年來鈦金屬在牙醫界越來越受到重視。牙醫師除了將鈦金屬應用於牙科植體外，也利用鈦金屬來製作活動假牙支架、固定牙橋及牙冠1-4。但是鈦金屬應用於牙科的過程並非全然沒有問題。本實驗的目的是要研究陶瓷燒付鈦金屬贗復物在不同燒瓷方式下，接受週期性疲勞應力後對結合強度所產生之影響。燒瓷步驟依黏結劑的使用狀況分為三大組：（I）使用黏結劑（Ⅱ）不用結合劑（Ⅲ）黏結劑與不透明陶瓷等比例混合；每一大組又依氬氣供給的狀況分為三小組：（A）全程真空燒瓷（不供應氬氣）（B）從750 ℃以上供應氬氣（C）全程供應氬氣。共計9小組試片，每組依不同燒瓷條件製作12 片，總數為108 片。週期性疲勞應力試驗後，觀察並記錄試片表面裂縫發生情形，每組各取二片觀察試片縱斷面。再將各組剩餘的十片試片在萬能測試機接受三點彎曲試驗。三點彎曲試驗形成的破斷面使用光學顯微鏡觀察，再利用掃描式電子顯微鏡，並進行EDS（Energy dispersive spectrometer）定性分析。將三點彎曲試驗得到的數值利用統計軟體（JUMP 4.0 ,SASInstitute,USA）進行雙因子變異數分析（two-wayANOVA ），及涂凱氏事後比較（Tukey HSDcomparison）。使用黏結劑的狀況出現統計學上的顯著差異（p <0.05），氬氣的供應狀況亦有差異（p ＝0.0482<0.05），但其p 值與.05 顯著水準相當接近。使用黏結劑的狀況與氬氣的供應方式有交互作用存在（p <0.05）。各組試片接受疲勞試驗後，在陶瓷表面都有百分之十至百分之六十左右的裂縫發生。不同的氬氣供應條件下燒瓷，有不同的氣泡產生率。試片接受週期數為104次的疲勞應力試驗後，裂縫的延伸多是從陶瓷層延伸到金屬與陶瓷層的交界面。在週期性疲勞應力作用下，陶瓷表面裂縫的發生率與陶瓷層氣泡的發生率相似。透過掃瞄電子顯微鏡的觀察及EDS 分析，可知破斷面的模式為adhesive/mixing形式。將本實驗結果與我們先前的研究比較發現，氧化程度愈高，則瓷－鈦金屬試片在週期性疲勞應力作用後的破壞應力值愈低。由統計結果也可看出，在週期性疲勞應力作用下，氧化層厚度對於破壞應力的影響遠比陶瓷本身的缺陷（氣泡和氣孔）來的重要，但燒瓷過程中所形成的氣泡對於破壞應力的影響也不容忽視。 Titanium is getting more and more interests in dentistry.However,the bonding of ceramic to titanium is still remaining problems.The purpose of this study was to evaluate the flexural bond strength of titanium-ceramic system under different firing cycles (or different bonding agents applying)after cyclic fatigue loading and compare the result of our previous study.The fired square-shaped (7mm x7mm)porcelain layer covered an area of central portion of one side of a metal specimen (0.7 x 7 x 20 mm) for a total thickness of 1.0 mm ceramic thickness achieved. In total,108 specimens were divided into three groups as follows:Group I -applied bonder,opaque and body porcelain;Group II -applied opaque and body porcelain; Group III -applied bonder/opaque mixed and body porcelain.And then each group was divided into three subgroups for different argon supplied:A)no argon supplied;B)argon supplied from 750 o C;C)argon supplied from the beginning.All the specimens were submitted to 10 4 fatigue cycles under 40Kgf at a 10Hz frequency loading.Cross-section of two tested specimen in each subgroup were examined by SEM.After that the rest 10 specimens in each subgroup were subjected to a three-point bending test,and the load of bond failure, called “fracture loads ”in this study were recorded.A two-way ANOVA followed by a Tukey posterior multiple comparisons were used to analyze the data.And both optical microscope and SEM with EDS examined the fracture surfaces.The cracking incidence of each subgroup was different between 10%and 60%.The incidences of bubbles in the ceramic layer were different under the three argon supplied firing schedules.The fracture loads of bonder/opaque mixed together (Group III)did show a statistically significant higher than applied bonder and opaque (Group I)(p<0.05)or no bonder group (Group II)(p<0.05),and there was statistically significant difference among the different argon supplied firing schedules (p=0.048<0.05)but close to the p level (0.05).The fracture surfaces analysis showed that the fracture mode was adhesive or mixing type.It was concluded that ceramic bonder or firing times could be the most important factor of the fracture loads of titanium-ceramic under cyclic fatigue loading due to reduce the oxide layer because of less damage under cyclic fatigue loads.
