The effects of heat treatment files and taper lock depth on the torsional fatigue resistance of rotary NiTi instruments

Viola Shelvannia Haryanto; Rosita Stefani; Eddy Eddy; Bernard Ongkie  Iskandar

doi:10.34011/jmp2k.v36i1.4190

Authors

Viola Shelvannia Haryanto Universitas Trisakti, Jakarta, Indonesia, Indonesia
Rosita Stefani Universitas Trisakti, Jakarta, Indonesia, Indonesia
Eddy Universitas Trisakti, Jakarta, Indonesia, Indonesia
Bernard Ongkie Iskandar Universitas Trisakti, Jakarta, Indonesia, Indonesia

DOI:

https://doi.org/10.34011/jmp2k.v36i1.4190

Keywords:

blue heat treatment, gold heat treatment, taper lock, torsional fatigue

Abstract

Background: A file fracture is a significant complication in endodontic treatment, particularly when it obstructs access to the apical root canal. The primary cause is torsional fatigue, occurring when applied force exceeds the elastic limit of NiTi alloys. Heat-treated rotary files have been developed to improve torsional resistance.

Objective: To compare the time to fracture due to torsional fatigue between gold and blue heat-treated rotary files under taper lock conditions.

Methods: A total of 48 heat-treated rotary files (#25.04) were embedded in bulk-fill composite resin blocks to simulate taper lock. Samples were randomly divided into eight groups (n=6): E-Flex Gold (3 mm, 5 mm), EndoArt Smart Gold (3 mm, 5 mm), E-Flex Blue (3 mm, 5 mm), and EndoArt Smart Blue (3 mm, 5 mm). Torsional fatigue time was recorded from the start of rotation using an endomotor until fracture occurred.

Results: One-way ANOVA revealed a statistically significant difference in torsional fatigue time among groups (p<0.05).

Conclusion: Blue heat-treated rotary files showed longer fracture times and may be safer in high taper lock conditions, although results are limited by the in vitro resin model.

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