Resilience Definition — MFDS Part 1 MCQ

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HardDental MaterialsResilience DefinitionMFDS Part 1

In a uniaxial tensile test, a dental alloy behaves linearly elastically up to its proportional limit, σp. The strain-energy density being reported is the area under the stress–strain curve from zero strain to the proportional limit and, for this material, is calculated as σp²/(2E), where E is Young's modulus. Which mechanical property does this represent?

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Correct answer: E — Modulus of resilience

The correct answer is E, modulus of resilience. It is the maximum elastic strain energy absorbed per unit volume before departure from elastic behaviour; graphically, it is the area under the stress–strain curve up to the proportional limit. For a linear elastic material, this equals σp²/(2E). Modulus of toughness is the total energy per unit volume absorbed up to fracture and therefore includes plastic deformation. Fatigue resistance concerns failure under repeated cyclic loading, while creep resistance concerns time-dependent deformation under sustained stress. Hardness is resistance to localised indentation, scratching or penetration and is not an energy-density measurement.

Reference: Niem T, Youssef N, Wöstmann B. Energy dissipation capacities of CAD-CAM restorative materials: A comparative evaluation of resilience and toughness. Journal of Prosthetic Dentistry. 2019;121(1):101-109. https://pubmed.ncbi.nlm.nih.gov/30017162/