Poster Presentation

Poster Presentation

PR84 - The Evaluation of the Elastic Limits Using Repetitive Torsional Loading on Reciproc Blue

Thursday, April 26
10:00 AM - 1:00 PM
Room: Exhibit Hall

Introduction: Reciprocating nickel-titanium (NiTi) instruments made of different alloy were investigated for the torsional elastic limit angle. Methods: Two reciprocating systems (Reciproc R25 and Reciproc Blue R25) were tested for two torsional conditions using a custom-designed testing device. The first test condition fixed the file tip at 3 mm and repetitively rotated them with gradually increasing angles, from 10 degree up to 270 degree, and resulting torque values were recorded (n=15). The second test subjected the file to a single continuous rotation until fracture (n=15). The super-elastic limits of the instruments were determined from their torque-rotation curves. Statistical analysis was performed independent t-test at 95% significance level. The tested specimens were examined under a scanning electron microscope (SEM). Results: It was found that the angle at the super-elastic limit was higher for Reciproc Blue than Reciproc regardless of test mode (p<.05). Repetitive torsional loading with gradually increasing rotational angle reduced the torsional resistance compared to the single rotation motion. At the 3 mm fixation level all files had super-elastic limit angles higher than the 170 degrees set in the dedicated reciprocating motor. SEM evaluation of the lateral aspects showed numerous longitudinal micro-cracks running along the long axis of the file shaft. For Reciproc Blue groups, machining groove of file shaft was distorted after both repetitive and continuous torsional tests. Conclusion: Under the conditions of this study, the 170 degrees set angle of dedicated motors for the Reciproc is proper to apply to Reciproc Blue as well.

Jung-Hong Ha

Associate Professor
Kyungpook National University

He has graduated from the Kyungpook National University and got his phD degree at the Pusan National University. He is now a full time professor at the Kyungpook National University and lecturing at the same university. His major research scope is endodontic instruments and materials in clinic.

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Sang Won Kwak

Assistant Professor / Pusan National University School of Dentistry
Pusan National University

Dr. Kwak is a full time professor at the Pusan National University and lecturing the Endodontics. His major research scope is endodontics materials and clinical methods.

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Hyeon Cheol Kim

Professor
Pusan National University, Busan, South Korea

Prof. Kim graduated from the Pusan National University and got the phD degree at the same University and now he is in charge of Vice Dean, Professor, Pusan National University School of Dentistry
Chair, Dept. of Conservative Dentistry
APEC Secretary, Asian Pacific Endodontic Confederation
Director of Scientific Committee, 2018 IFEA WEC Seoul
Associate Editor in the Restorative Dentistry & Endodontics
Active Reviewer in Journal of Endodontics
Main research scope is the Endodontic instruments and materials, especially the nickel-titanium instruments

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