- 學位論文
鎳鈦旋轉器械之動態測試及有限元素分析
Dynamic Test and Finite Element Analysis of Nickel-Titanium Rotary Instrumentation
摘要
隨著材料與製程技術進步，發展出鎳鈦合金的根管治療器械，適合應付彎曲的根管。本研究所使用的根管銼為ProTaper® Universal System鎳鈦旋轉器械。由文獻得知鎳鈦旋轉器械最常發生的斷裂情形有二種，分別為扭轉斷裂與疲勞斷裂。由於一般臨床實驗無法容易量測到器械動態行為時的各項數據，為了能在實驗中準確的量測出旋轉器械進入彎曲根管發生的動力學參數，如所承受之扭矩、正向力及進入根管的距離等。因此，本研究團隊發展出一套精密動態偵測裝置，利用此裝置進行一系列器械動態行為實驗，並與有限元素分析進行比較及驗證。實驗部份分為疲勞試驗、根管清創過程試驗與扭斷試驗，各別比較於有限元素分析之不鏽鋼彎道模擬以及扭轉模擬。結果發現疲勞試驗與不鏽鋼彎道模擬有其一致性。器械於進入彎道深度越深與彎道曲率半徑越小者，會使盟麥斯應力提升和器械抵抗疲勞的能力降低，發生斷裂的位置亦會往器械冠端移動。扭斷試驗與扭轉模擬有相當程度的一致性，其誤差低於9%。越大型號的器械，將其扭斷的扭矩則需要越大，但能承受扭轉的角度卻越少。由根管清創過程試驗，可以發現修形人工牙根管出現最大的正向力為器械S1，最小正向力為器械S2。建議臨床牙醫師在使用PTU F2器械時，要格外注意。
並列摘要
For conventional endodontic treatment, because of the limitation of material development and the complexity of the root canal system, broken instrument might be a problem during instrumentation. These accidents will make the treatment become more complex and should be avoided in clinical practice. With the advancement of material technology, Nickel-titanium(Ni-Ti) endodontic instruments were introduced to facilitate the instrumentation of curved canals. Its flexibility effectively minimizes the unfavorable side effects on the preparation of small and curved canals. From literatures, two fracture patterns of broken instruments happened most frequently; they are torsional fracture and fatigue fracture, respectively. Because it is difficult for clinical trials to objectively measure the torsional loads and other physical parameters during preparation of curved canals. In order to record events of Ni-Ti rotary instruments such as the torque, normal force, and distance of the preparation during the shaping of straight and curved canals in resin blocks. Thus, the current study developed a special computer testing platform to test the experimental specimens of ProTaper® Universal System. The experiment includes fatigue test, preparation of curved canals test and torsional fracture test. They will be stimulated by the Finite Element Analysis in the following conditions: stainless steel curved canal simulation, artificial resin block simulation and torsional simulation. Result showed that the fatigue test and the stainless steel curve simulation has its uniformity. The deeper curve depth and smaller curvature radius would cause the increase of von Mises stress and the reduction of instrument’s fatigue resistance ability. The break position also moved toward the crown end of instrument. The torsional fracture test and the torsional simulation were consistent. The results of the experiment and the FEA were all within 9% difference. The study indicated that the fracture torque was increased and the torsional angle was decreased by increasing the instrument size. According to the testing results, the largest normal force was measured in S1 and the smallest normal force was measured in S2. The study results suggested that the clinical dentist would be more attention to use PTU F2 instrument in endodontic treatment.