A patient with epilepsy needs a posterior crown and dislikes the metal margin visible on his existing #19 restoration. What is the best option?

Correct answer: D. Monolithic zirconia

• A. Cast gold is highly durable but is a metal restoration and does not address the esthetic complaint.
• B. Porcelain fused to metal reintroduces the very metal margin the patient objects to.
• C. Feldspathic porcelain has low flexural strength, around 60 to 70 MPa, and is entirely unsuitable for a posterior full-coverage restoration.
• D. CORRECT. Monolithic zirconia gives high flexural strength — around 900 to 1200 MPa — with no metal substructure and therefore no grey margin. The strength matters here because a patient with epilepsy may sustain occlusal trauma during a seizure, and zirconia is the most fracture-resistant tooth-coloured option available for a posterior tooth.

Note: Ranked flexural strengths worth remembering: feldspathic porcelain 60–70 MPa, leucite-reinforced roughly 120 MPa, lithium disilicate (e.max) 350–400 MPa, and zirconia 900–1200 MPa. Trade-off: as strength rises, translucency falls, which is why zirconia is favoured posteriorly and lithium disilicate anteriorly.