Prosthodontics & Occlusion · patient case question
The patient is unhappy with the grey band at the margin of her existing crown. Which restorative material best addresses this?
Patient case: Failing anterior bridge and a collapsed posterior bite
Patient: Female, 68 years old
Chief complaint: “My front bridge is loose, and my temporary cap fell off while I was eating.”
History: Hyperlipidaemia, depression. Medications: atorvastatin, citalopram.
Findings: Anterior fixed partial denture is mobile as a unit. An existing metal-ceramic crown on tooth #14 shows a grey band at the gingival margin. Diagnostic casts show the mandibular left posterior segment supra-erupted into the opposing edentulous space. A new all-ceramic crown is being tried in on tooth #30.
Show answer and explanation
Correct answer: C. Zirconia
- A. A metal-ceramic crown with a metal collar reproduces exactly the problem being solved.
- B. A full gold crown eliminates grey but replaces it with gold — unacceptable in a patient raising an aesthetic complaint.
- C. CORRECT. The grey band is the metal substructure of a metal-ceramic crown showing through thin marginal tissue, made worse as recession exposes the collar. ZIRCONIA is metal-free, so there is no dark substructure and no grey shadow at the margin, and it also avoids the metal-ion gingival discolouration that can accompany base-metal alloys. Modern translucent zirconia gives acceptable aesthetics with strength well above lithium disilicate.
- D. An amalgam core would be visible through any translucent ceramic and can also cause its own greyish tattoo of the adjacent tissue.
Note: The other lever is margin placement. A supragingival or equigingival margin on a metal-free restoration avoids the problem entirely and is far kinder to the periodontium than chasing the aesthetics subgingivally.
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