Amalgam Creep — MFDS Part 1 MCQ
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Correct answer: E — A progressive increase in strain with time while the stress is maintained
Option E is correct. Creep is the time-dependent increase in strain that occurs while a set material is subjected to a maintained stress. In amalgam, sustained loading can therefore produce progressive deformation, with the magnitude depending on factors including stress, temperature and alloy composition. Option C describes elastic deformation and recovery rather than creep. Option A is setting contraction or expansion, which results from the amalgamation reaction rather than prolonged loading. Option D describes corrosion, an electrochemical process that is distinct from mechanical deformation. Option B describes thermal expansion or contraction. The wording avoids defining creep as invariably and completely permanent because experimental amalgams may exhibit a recoverable viscoelastic component after unloading.
Reference: Greener EH, Szurgot K, Lautenschlager EP. The creep compliance of dental amalgam in the stress range of 20-80 MPa. Journal of Biomedical Materials Research. 1982;16(5):599-608. https://pubmed.ncbi.nlm.nih.gov/7130215/