Polyether Properties — MFDS Part 1 MCQ
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Correct answer: C — High stiffness after setting, complicating removal from pronounced undercuts
The correct answer is C. Conventional polyether becomes relatively stiff after setting, so an impression engaging pronounced interproximal or other anatomical undercuts may require substantial force to remove and should be managed cautiously. Comparative testing has found polyether to be the stiffest among tested elastomers and to require greater removal force, although stiffness alone does not fully predict that force. Polyether is inherently hydrophilic rather than hydrophobic and has generally good dimensional stability when protected from water absorption. Working time varies between formulations, so it is not invariably short. Its setting reaction does not depend on loss of a volatile by-product.
Reference: Papadogiannis D et al. Effect of storage time on the viscoelastic properties of elastomeric impression materials. Journal of Prosthodontic Research. 2012;56(1):11–18. https://pubmed.ncbi.nlm.nih.gov/21596649/; Walker MP et al. Correlation of impression removal force with elastomeric impression material rigidity and hardness. Journal of Prosthodontics. 2013;22(5):362–366. https://pubmed.ncbi.nlm.nih.gov/23387301/