Dental Alloy Classification — MFDS Part 1 MCQ

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HardDental MaterialsDental Alloy ClassificationMFDS Part 1

Using the ADA compositional classification of dental casting alloys, which of the following alloys is classified as high noble? All compositions are percentages by weight.

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Correct answer: A — 40% gold, 20% palladium and 40% copper

Option A is high noble because it contains 60% noble metal in total (40% gold plus 20% palladium), including the required 40% gold. Both thresholds must be satisfied. Option B reaches 60% total noble metal but contains only 39% gold. Option D contains 40% gold but only 59% total noble metal. Option E contains 25% noble metal and therefore meets the threshold for the noble category, not high noble. Titanium in option C is a base metal for this classification and does not contribute to noble-metal content. The original keyed definition was correct, but the item has been converted from straightforward recall into a more discriminating compositional application suitable for the specified Hard tier.

Reference: American Dental Association Council on Dental Materials, Instruments, and Equipment. Classification and definition of alloys used for casting substrates for porcelain veneering. Journal of the American Dental Association. 1981;103(5):755-757. https://pubmed.ncbi.nlm.nih.gov/6946143/