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標題: | 矯正用迷你骨釘系統之機械測試及有限元素分析 Mechanical and Finite Element Analysis of Mini-screw Systems for Orthodontic Anchorage |
作者: | Yuan-Yi Tung 童元釔 |
指導教授: | 林俊彬 |
關鍵字: | 矯正用迷你骨釘,迷你骨釘穩定性,植入扭力,有限元素分析, orthodontic mini-screws,the stability of mini-screws,insertional torque,finite element analysis, |
出版年 : | 2008 |
學位: | 碩士 |
摘要: | 近年來,隨著骨性錨定應用於齒顎矯正的需求性提高,各種不同設計的迷你骨釘陸續被研發且廣泛應用於臨床治療,許多研究已證實矯正用迷你骨釘的臨床效益,但目前臨床上仍存在待解決之問題包括: 骨釘周圍軟組織發炎、使用中鬆脫或植入骨釘斷裂的情形,再者,有關矯正骨釘本身機械性質測試的基礎研究相對較少,故本實驗的目的在探討迷你骨釘的螺紋深度、中心錐度及錐形圈數等幾何設計,對於植入扭力、植體穩定性及骨釘和周圍骨頭應力集中的影響,並與有限元素分析進行驗證,其結果將作為日後迷你骨釘設計的準則。
本實驗包括兩部份,第一部份乃評估兩家市售之迷你骨釘(Mondeal, German; Osstem, Korea)的機械性質表現; 第二個部份將利用四種自製的迷你骨釘,以分析植體的幾何參數(螺紋深度(mm)/中心錐度(°)/錐形圈數(c))對於機械特性的影響,四種骨釘分別為 s1(0.4/7/4)、s2(0.4/0/0)、s3(0.4/7/2)、s4(0.32/7/2)。實驗流程如下: (1) 以有限元素方式利用彎矩與抗拉測試分析,評估在不同螺紋參數改變下,迷你骨釘本身的應力分佈與位移量。(2) 以有限元素分析的設計所製作出四種骨釘,及兩種市售迷你骨釘,分別進行植入扭力及抗拉出能力的測試,並以0.48 g/cc的人造假骨作為植入體。(3) 選取s1骨釘進行彎矩測試,以應變規量測人造假骨表面應變的變化,驗證有限元素分析結果,間接得知骨釘及骨頭周圍應力集中狀況。實驗結果如下: 植入扭力值比較為Osstem(26.19 ± 1.36 Ncm) > Mondeal(17.86 ± 1.24 Ncm),s1(28.79 ± 2.59 Ncm) > s3(24.20 ± 1.11 Ncm),s3(24.20 ± 1.11 Ncm) > s2(21.78 ± 1.83 Ncm) 及s3(24.20 ± 1.11 Ncm) > s4(21.39 ± 0.49 Ncm); 最大抗拉力量的比較為Osstem(138.15 ± 9.87N) > Mondeal(95.09 ± 17.19N),s1(113.9 ± 8.37N) > s3(81.44 ± 6.77N),s2(96.63 ± 6.7N) > s3(81.44 ± 6.77N) 及s4(102.9 ± 12.8N) > s3(81.44 ± 6.77N)。 本研究結論如下: 1. Osstem比Mondeal具較高的植入扭力及抗拉出能力。 2. 適度增加螺紋深度、錐度與錐形圈數將提高植入扭力及抗拉出能力。 3. 過大的螺紋深度、錐度或錐形圈數反而會減低抗拉能力。 4. 有限元素分析可作為迷你骨釘受力時應力集中分析之研究工具。 Recently, the use of skeletal anchorage is increasingly popular in modern clinical orthodontics. Many different designs of miniscrews were developed and widely applied in clinics, and their advantages have been proved by many studies. However, there were still some problems to be solved during clinical use of orthodontic miniscrews, including surrounding soft tissue inflammation, loosening in use, or breakage during implantation. Moreover, the mechanical properties of orthodontic miniscrews have few been studied. Therefore, the purpose of the study is to investigate the effects of geometrical parameters, including thread depth, taper of core, and circles of taper of miniscrews on its insertional torque, pullout strength, and stress distribution. These mechanical properties were assessed using standardized laboratory set-up and finite element analysis (FEA). The results will be applied to the development of new miniscrew systems in the future. The study includes two parts. Part I was to evaluate the mechanical behavior of two commercial available miniscrews (Mondeal, German; Osstem, Korea). Part II was to analyze how the following geometric properties would affect the mechanical performance with four custom-made miniscrews. They have different designs in thread depth(mm)/taper of core(°)/circles of taper(c): s1(0.4/7/4)、s2(0.4/0/0)、s3(0.4/7/2)、s4(0.32/7/2). The procedures were as follows: (1) To evaluate how the different geometrical parameters will affect the stress distribution and displacement of miniscrews during bending and pullout test simulated by FEA. (2) Mechanical tests for insertion and pullout, and the samples were four custom-made miniscrews developed according to the designs of FEA and two other commercial miniscrews. The bone were used with Sawbones (0.48g/cc). (3) Choosing s1 for mechanical bending test and measuring the strain on the surface of the Sawbones surrounding the miniscrews with strain gauge. This result will be compared with the result of the FEA and get the stress distribution around the miniscrews indirectly. The results of this study were listed as follows, the comparison of the insertional torque: Osstem(26.19 ± 1.36 Ncm) > Mondeal(17.86 ± 1.24 Ncm), s1(28.79 ± 2.59 Ncm) > s3(24.20 ± 1.11 Ncm), s3(24.20 ± 1.11 Ncm) > s2(21.78 ± 1.83 Ncm), and s3(24.20 ± 1.11 Ncm) > s4(21.39 ± 0.49 Ncm); the comparison of the maximum pullout force: Osstem(138.15 ± 9.87N) > Mondeal(95.09 ± 17.19N), s1(113.9 ± 8.37N) > s3(81.44 ± 6.77N), s2(96.63 ± 6.7N) > s3(81.44 ± 6.77N), and s4(102.9 ± 12.8N) > s3(81.44 ± 6.77N). The conclusion were: 1. Both the insertional torque and the resistance to pull-out test of the Osstem miniscrew were higher than those of Mondeal. 2. An appropriate increase in thread depth, taper of the core, and thread number at the taper part of miniscrew resulted in larger insertion torque, increased resistance to pullout, which implied better retention. 3. Exaggerated increase of thread depth, taper of the core or the circles of taper will decrease the resistance to pullout. 4. FEA is a good tool for studying the stress and strain distribution of miniscrews subjected to loading. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/37996 |
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顯示於系所單位: | 臨床牙醫學研究所 |
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