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Park, Sei Joo

University of British Columbia

Objective: The study evaluated the effect of canal curvature locations, rotational speeds, and vertical stroke lengths on the cyclic fatigue resistance of XP-3D Shaper (XPS; FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) files in customized artificial canals at a body temperature with a dynamic motion. Methods: One hundred and twenty XPS (25 mm length, 30 ISO tip diameter, 0.01 taper) files were subjected to cyclic fatigue testing inside tapered artificial canals with a tip diameter of 0.40 mm, a curvature of 60˚, a 3 mm radius, and two different curvature locations with the centres of curvatures placed at 5 mm and 8 mm from the coronal opening. The experiment was video recorded, and each instrument was rotated by an 8:1 reduction handpiece connected to a ProMark torque-controlled endodontic motor (Dentsply Tulsa Dental Specialties, Tulsa, OK) with defined in-and-out axial movements until a visible fracture was observed. The rotation speeds were set at 1000 revolutions per minute (rpm) or 3000 rpm by the electric motor, and the repetitive axial movements of 3 mm or 6 mm were performed by a Hydraulic Instron Universal testing machine (Instron, Norwood, MA) at the speed of 1 mm per second. The time to fracture was measured in seconds, and the Number of Cycles to Fracture (NCF) was calculated. The length of each fractured instrument was also examined. The data were analyzed using an independent sample t-test and multiple linear regression, with the significance threshold set at p<0.05. Results: XPS instruments tested at the lower 1000 rpm rotation had increased NCF compared to the files rotated at the higher 3000 rpm. XPS files subjected to long 6 mm vertical strokes showed greater NCF than those moved with short 3 mm axial motions. The locations of canal curvature, coronal or middle, did not have a significant effect on the NCF of the XPS files. Conclusion: Within the limitations of the study, long vertical strokes and lower rotation speed reduced the file separation inside a curved canal. The canal curvature location did not influence the NCF of XPS files.

Text

2024-05-31

Attribution-NoDerivatives 4.0 International

http://hdl.handle.net/2429/85168

Craniofacial Science

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nd/4.0/