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Torsional fatigue and endurance limit of a size 30 .06 ProFile rotary instrument
Author(s) -
Best S.,
Watson P.,
Pilliar R.,
Kulkarni G. G. K.,
Yared G.
Publication year - 2004
Publication title -
international endodontic journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.988
H-Index - 119
eISSN - 1365-2591
pISSN - 0143-2885
DOI - 10.1111/j.1365-2591.2004.00814.x
Subject(s) - standard deviation , deflection (physics) , mathematics , fracture (geology) , cyclic stress , nickel titanium , materials science , orthodontics , statistics , composite material , medicine , physics , shape memory alloy , optics
Aim To evaluate the torsional cyclic fatigue characteristics and specifically the endurance limit (EL) of a nickel–titanium rotary instrument. Methodology Size 30 .06 taper ProFile instruments were evaluated. The equipment was assembled according to the ANSI/ADA Specification No. 28. The motor was programmed to repeatedly rotate to a selected deflection angle (DA) and then return to zero (cycle). Testing started at 200° and was continued at decreasing angles until 10 6 cycles were reached without instrument fracture. Ten instruments were tested at each DA. The mean log number of cycles to fracture and standard deviation were determined for each DA at which fracture occurred. The DA at which 10 6 cycles were reached without instrument fracture corresponded by definition to the EL. Analysis of variance and pairwise comparisons using Duncan's multiple range test were performed to detect significant differences among the mean log number of cycles of the different DA. Significance was determined at the 95% confidence level. Results Instruments cycled at larger DA consistently demonstrated fewer cycles to fracture than those cycled at smaller DA. The differences among the mean log number of cycles of the different DA were statistically significant ( P < 0.001). Cycles of 10 6 were completed without instrument fracture at 2.5°. Conclusions A torsional fatigue profile was generated for a specific NiTi rotary instrument. The EL was 2.5°.