Prosthodontics & Occlusion · single question
What material is used to fabricate the metal framework for a removable partial denture (RPD)?
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Correct answer: B. Base metal alloy (cobalt-chromium)
The metal framework for removable partial dentures (RPDs) is most commonly fabricated from cobalt-chromium (Co-Cr) base metal alloy. Cobalt-chromium offers several advantages for RPD frameworks: high strength and rigidity (allowing thin, non-bulky design), good biocompatibility, corrosion resistance, lower density than gold alloys (lighter weight), and cost-effectiveness compared to noble metal alloys. The framework is typically cast using the lost-wax technique or, increasingly, fabricated using selective laser melting (SLM) digital technology. Noble (gold) alloys were historically used but have been largely replaced by cobalt-chromium due to cost and property advantages.
- A. Semi-noble alloys are used in some fixed restorations but are not standard for RPD frameworks. Base metal (Co-Cr) is standard.
- B. RPD metal frameworks are fabricated from BASE METAL alloys — most commonly cobalt-chromium (Co-Cr). Base metal alloys are preferred for RPD due to their high stiffness (resists deformation), excellent rigidity for clasps, biocompatibility, and low cost compared to noble metals.
- C. Titanium RPD frameworks exist but are uncommon due to casting difficulties and higher cost. Co-Cr base metal is the most commonly tested material.
- D. Noble metals (gold alloys) are too soft/flexible for RPD clasps. They would not provide adequate rigidity for RPD framework design.
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