Endodontic Files — MFDS Part 1 MCQ

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ModerateRestorative PrinciplesEndodontic FilesMFDS Part 1

When files of comparable dimensions and cross-sectional design are used to shape a curved root canal, what is the principal clinical advantage of nickel-titanium files over conventional stainless steel files?

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Correct answer: B — Greater flexibility, with better preservation of canal curvature

Nickel-titanium files are more flexible than comparable stainless steel files because the alloy has a lower elastic modulus and exhibits superelastic behaviour. In curved canals, this allows the instrument to follow the original canal path more closely, reducing transportation, ledge formation and other shaping errors. Cutting efficiency depends substantially on cross-sectional design, rake angle and method of use, so it is not an inherent universal advantage of NiTi. NiTi instruments are generally not cheaper. They may fracture through torsional overload or cyclic fatigue and therefore do not have greater resistance to every mode of separation. Greater radiopacity is not their principal clinical advantage.

Reference: Leal da Silva EJ, Martins JNR, Versiani MA. NiTi instruments in endodontics: contemporary concepts, principles, and practical guidance. Brazilian Oral Research. 2026;40:e027. https://pubmed.ncbi.nlm.nih.gov/42138960/