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Dental Casting Alloys & Investment

Dental Materials • NEET MDS Study Guide • AI-Generated Notes

⭐ High-Yield Facts for Exam

  • Type I gold = inlays (soft); Type IV = frameworks (extra-hard).
  • Ni-Cr/Co-Cr = common base metals.
  • Co-Cr = RPD frameworks.
  • Gypsum-bonded investment = gold.
  • Phosphate-bonded = base metals/ceramics.

Casting Alloys & Investments

Gold Casting Alloys (Type I-IV)

  • Type I (soft) — inlays under low stress.
  • Type II (medium) — inlays/onlays.
  • Type III (hard) — crowns, short-span FPDs.
  • Type IV (extra-hard) — RPD frameworks, long-span FPDs (highest strength).

Base Metal Alloys

Nickel-chromium and cobalt-chromium are common; Co-Cr is widely used for RPD frameworks (light, stiff).

Investments

  • Gypsum-bonded — for conventional gold casting (lower temperatures).
  • Phosphate-bonded — for high-fusing base metal alloys and ceramics.

Exam Tips ⭐

Type IV gold = strongest (frameworks); gypsum-bonded for gold; phosphate-bonded for base metals.

📝 Practice MCQs — Dental Casting Alloys & Investment

Q1. Which gold casting alloy is used for RPD frameworks?
A. Type I
B. Type II
C. Type III
D. Type IV
Show Answer
✅ Answer: D
Type IV (extra-hard) gold is used for frameworks/long-span FPDs.
Q2. Gypsum-bonded investment is used for casting:
A. Base metal alloys
B. Gold alloys
C. Ceramics only
D. Acrylics
Show Answer
✅ Answer: B
Gypsum-bonded investment suits lower-temperature gold casting.
Q3. Which investment is used for high-fusing base metal alloys?
A. Gypsum-bonded
B. Phosphate-bonded
C. Plaster
D. Alginate
Show Answer
✅ Answer: B
Phosphate-bonded investments tolerate high casting temperatures.
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Related Topics

Dental Ceramics — Types & SystemsMechanical Properties of MaterialsDental Cements — ZPC, GIC, Resin