臺灣博碩士論文加值系統

由於材料和技術的限制，臨床上無法得到一個完全無施力密合的補綴物，當金螺釘把達到臨床上可接受的密合度的補綴物鎖緊在支台(或植入體)之上，靜態應力於是產生。本體外實驗以應變計法觀察(1)不同的金屬床-支台不密合度、(2)不同的鎖緊金螺釘的順序、(3)不同的金屬床材質對金屬床與支台上靜態應力的形成與分佈的影響。實驗的模型與金屬床乃根據下顎第一小白齒至第一大白齒種植體支持陶瓷熔合金屬牙橋來設計。應變計位於金屬床近、遠心關節的咬合面及大、小白齒支台的近、遠心側。以金屬床關節的彎曲及支台的彎曲表示系統應力分佈的形態並以重複測試二方、三方變異數分析(重複因子：不同的鎖緊金螺釘的順序)進行檢定。結果顯示不密合度越大彎曲越強烈(P<0.001)；不同的鎖緊金螺釘的順序也有著統計上顯著的差異(P<0.001)，不過在不密合度、金屬床材質相同的情況下，雖然鎖緊金螺釘的順序不同，但金屬床關節及支台表面呈現類似的應力分佈形態。Ag-pd金屬床與GoId金屬床兩者的應力分佈形態在不密合度小的時候顯著的不同(P＜0.001)，但隨不密合度增加越見相似。由資料顯示Ag-pd金屬床105μm不密合度、Gold金屬床45μm和135μm不密合度皆無法以鎖緊金螺釘來關閉。這些結果顯示金屬床-支台不密合的程度對金屬床及支台表面的應力分佈有強而顯著的影響，不同的鎖緊金螺釘的順序有其影響雖顯著但較前項條件為小，而不同的金屬床材質對應力分佈的影響在不密合度小的情況下較顯著。

Clinically, a perfectly passive-fit prosthesis is desired but difficult to obtain due to the material and technical limitations. When a prosthesis of clinically acceptable fit is tightened on the abutments (or fixtures), static stresses are generated in the framework and abutments (or fixtures). Tills in vitro study utilized strain-gauge technique to evaluate the effect of (1) different framework-abutment fitting inaccuracies, (2) different sequences of gold screw tightening, and (3) different framework materials on the distribution of stresses generated on die framework and abutments. Models and frameworks were designed according to a three-unit implant-supported porcelain fused to metal bridge with fixtures replacing lower first premolar and lower first molar. Strain gauges were bonded on the occlusal surfaces of the frameworks and die mesial and distal surfaces of the abutments. Bending of die joints of the frameworks and the abutments were defined and were used to represent how stresses were distributed. Two-way and three-way ANOVA for repeated measures with methods (screw-tightening sequences) were applied for statistical analysis. The data showed that bending increased significantly with increase in fitting inaccuracy (P<0.001). Under the same degree of fitting inaccuracy and with die same framework material, similar patterns of stress distribution were observed on the frameworks and abutments with different sequences of gold screw tightening. Significant differences (P<0.001) were observed in stress distribution of Ag-Pd (Jelstar) framework and Gold (Jelenko O) framework especially with small fitting inaccuracies; the pattern of stress distribution became similar as the degree of fitting inaccuracy increased. Strain-gauge data revealed that 105 μm fitting inaccuracy of Ag-Pd framework and 45μm and 135μm fitting inaccuracies of Gold framework could not be closed by means of tightening the gold screw. The data suggested that the degree of framework-abutment fitting inaccuracy has significant influence on the stress distributions of tire frameworks and abutments, the tightening sequence of gold screw has less significant effects on the stress distributions. The material of frameworks itself has significant effect on the stress distributions especially when the fitting inaccuracies are small.