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Investment Expansion — NDEB AFK MCQ

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HardDental MaterialsInvestment ExpansionNDEB AFK

Which dental material undergoes a setting expansion that can be utilised to compensate for metal casting shrinkage?

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

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Correct answer: E — Gypsum-bonded investment

Gypsum-bonded investments undergo thermal and hygroscopic setting expansion that compensates for the solidification shrinkage of cast metal alloys (approximately 1.5-2.5% shrinkage). The investment's setting expansion, hygroscopic expansion (if placed in water during setting), and thermal expansion during burnout collectively compensate for metal shrinkage, producing a well-fitting casting. Phosphate-bonded investments are used for higher-melting alloys.

Reference: Anusavice – Phillips' Science of Dental Materials, 13th ed., 2022