Dynamic Test and Finite Element Analysis of Nickel-Titanium Rotary Instrumentation

• Main Authors: YEN-YING CHEN, 陳彥穎
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/26037269061009100490

碩士 === 中原大學 === 醫學工程研究所 === 96 === 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.