Combining apical torsional load and cyclic fatigue resistance of NiTi instruments: New approach to determine the effective lifespan of rotary instruments. (1st March 2021)

• Record Type: Journal Article
• Authors: Iacono, Francesco; Pirani, Chiara; Gatto, Maria Rosaria; Prati, Carlo; Peters, Ove A.
• Is Part Of: Australian endodontic journal. Volume 47:Number 3(2021)
• Page Start: 429
• Page End: 434
• Publication Date: 2021-03-01
• Subjects: apparatus and instruments -- cyclic fatigue -- device -- endodontics -- NiTi instruments -- torsional load; Endodontics -- Periodicals; Endodontics -- Periodicals; 617.6342
• DOI: 10.1111/aej.12495
• Languages: English
• ISSNs: 1329-1947

Abstract

Abstract: In the described proof‐of‐principle experiments, we introduced a novel testing device to investigate how different concurrent torsional loads influence the cyclic fatigue (CF) resistance of a nickel–titanium (NiTi) instrument. The device was designed to test CF resistance of NiTi files with a standardized load on the apical 5 mm; a movable cylinder controlled by a lever provided a uniform real‐time load. Thirty‐three NiTi instruments 25.04 (F360, Komet, Lemgo, Germany) were rotated until fracture at 30° curvature under three different torsional loads ( n = 11 each); Group A: 2.5 Ncm; Group B: 5 Ncm; Group C: 10 Ncm. anova, multiple comparisons Tamhane tests, regression and Kaplan–Meyer analysis were performed to contrast means. Resistance to cyclic fatigue differed significantly among groups ( P = 0.0001). Increased torsional loads led to a decrease in time to failure. An inverse correlation ( r = −0.721, P = 0.001) was observed between time and torsional load, with higher torsional loads correlated to shorter times to fracture.