- 學位論文
牙科迷你骨釘螺紋設計之有限元素分析
Finite Element Analysis of Dental Mini-screw Thread Designs
摘要
牙科矯正治療中，迷你骨釘是用來抵抗移動牙齒時所產生的矯正力， 而迷你骨釘的鬆脫可能會使矯正失敗，過去臨床上研究迷你骨釘，大多是 利用鬆脫比例來代表迷你骨釘之穩定性，然而這些結果，無法反映迷你骨 釘以及顎骨內受力情形，也無法得知各種不同螺紋設計對於矯正時的影 響。因此，本文主要針對迷你骨釘與顎骨介面的結合強度做研究，本研究 目的以生物力學測試與有限元素分析方法，探討迷你骨釘螺紋設計因子對 於矯正時穩定性的影響，作為將來設計迷你骨釘之參考。本論文共分為二 個部分。第一部分:利用彎矩與抗拉分析，改變螺紋設計參數，錐形度數、 錐形圈數與螺紋高度，得到彎矩與抗拉時其力學行為，在生物力學測試中， 請廠商製作上述骨釘的其中四種，將迷你骨釘鎖入人造假骨中，並使用萬 用材料試驗機進行拉出測試。結果顯示，錐形度數與圈數的增加，可以提 升抗拉與彎矩能力的表現，而螺紋高度的增加可以增加抗拉能力，但有其 上限，有限元素分析與生物力學測試的結果有相同的趨勢。第二部份:研究 市面上三種不同形式的迷你骨釘，另外使用萬用材料試驗機進行三種廠牌 植體之拉出測試，由分析與實驗結果中得知，J-screw 有最好的抗拉與彎矩 能力，依序是Osstem 及Mini-2000。本研究建立之有限元素模型可預測生 物力學測試之結果，協助臨床醫師選擇迷你骨釘，並作為將來迷你骨釘設 計之參考。
並列摘要
Miniscrew is used as an anchorage for orthodontic tooth movement, and loosening of miniscrews might lead to orthodontic failure. In previous clinical studies, loosening rates of miniscrews are usually related to their stabilities, but these results can not reflect the inner stress distribution around miniscrews and jaw bone, neither show the relationship to the thread design. Therefore, this study investigated the combined strength between miniscrews and the jaw bone. The purpose of this study was to investigate the influence of thread designs on the stability of orthodontic miniscrews, by using biomechanical test and finite element analysis and to provide references for designing new miniscrews in the future. The study was divided into two main parts. Part 1: Using bending test and pullout test to estimate the effect of thread geometric designs, such as thread heights, degrees of taper and circles of tapering portions, to obtain the bending and pullout mechanical behavior. In the biomechanical test, we manufactured four of the fore-mentioned miniscrews, and inserted them to the foam bones (Sawbones® ) and used the material test machine to perform the pullout test. The results revealed that increasing degrees of taper and circles of tapering portions can increase bending strength and pullout strength, and increasing the thread heights can increase the pullout strength, but there is upper limit. Biomechanical test and finite element analysis have the same trend. Part 2: To investigate the three different commercial miniscrews, and use the material testing machine to perform the pullout test, the results indicate the J-screw (J-screw®) have best bending and pullout strength and the following was Osstem and Mondeal(mini-2000) in order. In conclusion, finite element model of the study could reliably reflect the results of biomechanical tests, and could assist dentists in choosing the miniscrew in clinics, and provide references as new miniscrew design.