Hardness Testing — MFDS Part 1 MCQ

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ModerateDental MaterialsHardness TestingMFDS Part 1

Which hardness test presses a square-based diamond pyramid into the surface of a dental material and determines hardness from the diagonals of the resulting square indentation?

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Correct answer: C — Vickers hardness test

The correct answer is **A, the Vickers hardness test**. It uses a square-based diamond pyramidal indenter. After a specified load is applied, the two diagonals of the approximately square indentation are measured and used to calculate the Vickers hardness number. Knoop testing also uses a diamond indenter, making the original stem potentially ambiguous, but its elongated geometry produces a rhomboidal indentation. Brinell testing uses a spherical ball indenter. Rockwell testing derives hardness primarily from indentation depth using a ball or conical diamond indenter. Shore testing measures rebound or indentation behaviour and is commonly applied to elastomeric or polymeric materials rather than using a square pyramidal impression.

Reference: Wassell RW, McCabe JF, Walls AW. Subsurface deformation associated with hardness measurements of composites. Dental Materials. 1992;8(4):218–223. https://pubmed.ncbi.nlm.nih.gov/1291387/