Prosthodontics & Occlusion · single question
A patient complains that their crown appears opaque near the gingiva. All of the following are causes EXCEPT:
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Correct answer: D. Wrong shade of opaque layer
- A. Under-preparation at the gingival margin leaves insufficient space for both metal and porcelain, resulting in opacity — this IS a true cause.
- B. Thick metal substructure (in PFM crowns) DOES cause opacity near the margin — it IS a true cause of this complaint.
- C. Insufficient porcelain thickness over the metal creates opacity — this IS a true cause of gingival opacity in PFM crowns.
- D. 'Wrong shade of opaque' is the EXCEPTION (NOT a cause of gingival opacity). The opaque layer's purpose is to block the dark metal color and create a base for porcelain layering. The WRONG shade of opaque would affect the overall crown color but would not specifically cause opacity at the gingival margin — the other listed causes are direct mechanical reasons for gingival opacity.
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