Question 296 (part 2) · LDEK · Crowns
Indicate true statements:
1) the thickness of metal coping in metal-porcelain crowns is od 0.3 to 0.4mm for non-precious alloys and 0.2 mm for precious alloys;
2) complex crown veneered with low-melting porcelain (850-10500C);
3) during modelling of the metal-porcelain crown, emergence angle should be of 0- 150;
4) in fabrication of metal-porcelain crowns in the lab, complex model cast from class III and class II plaster (base);
5) oxidation is the process during which a layer of oxides is formed, which is responsible for the fusion of gold coping with veneering ceramics.
Correct answer is:
2) complex crown veneered with low-melting porcelain (850-10500C);
3) during modelling of the metal-porcelain crown, emergence angle should be of 0- 150;
4) in fabrication of metal-porcelain crowns in the lab, complex model cast from class III and class II plaster (base);
5) oxidation is the process during which a layer of oxides is formed, which is responsible for the fusion of gold coping with veneering ceramics.
Correct answer is:
- A. only 1.
- B. 1,2,3,5.
- C. 3,4,5.
- D. 2,3.
- E. none of the above-mentioned.
Hint
Check each value: coping thickness for noble vs base alloys, firing range, emergence profile, die stone class and oxide formation on gold.
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