High-Copper Amalgam — MFDS Part 1 MCQ

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ModerateDental MaterialsHigh-Copper AmalgamMFDS Part 1

Compared with conventional low-copper dental amalgam, which property change is the principal consequence of increasing the copper content?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: C — Suppression of the gamma-2 phase, with less corrosion and creep

Explanation lettering: B = shown as A · C = shown as B · A = shown as C · E = shown as D · D = shown as E

Option A is correct. Increased copper causes tin to preferentially form the eta copper–tin phase, markedly reducing or eliminating the weak, corrosion-prone gamma-2 tin–mercury phase. Consequently, high-copper amalgam has lower corrosion susceptibility and creep, with improved strength and marginal durability. B is not the defining advantage: high-copper classification concerns the alloy's copper content and does not necessarily imply a lower final mercury fraction. C is false because amalgam remains metallic and unaesthetic. D is false because amalgam remains a good thermal conductor; increased copper does not provide pulpal insulation. E is false because amalgam does not chemically adhere to enamel or dentine without a separate bonding system.

Reference: Beech DR. High copper alloys for dental amalgam. International Dental Journal. 1982;32(3):240–251. https://www.widgetlibrary.knowledge.scot.nhs.uk/media/WidgetFiles/1003118/Bonded%20amalgam%20longevity%20bdj.2009%20Bonsor.pdf