Zirconia or lithium disilicate: choosing a material per tooth
The material decision is usually made per tooth, not per patient. Here is the rule we apply in the laboratory when the case is ambiguous.
Strength is not the only variable
Zirconia wins on strength and lithium disilicate wins on translucency, but the decision usually turns on three practical questions: how much enamel is left, how much occlusal load the tooth carries, and whether the clinician can bond.
A molar in a bruxist with a 0.6 mm occlusal space is a zirconia case. A central incisor with good enamel value and a cooperative patient is a glass-ceramic case. Everything in between depends on the detail.
The rule we use
Posterior teeth with heavy load, limited space or a history of ceramic fracture get monolithic 3Y-TZP. Anterior teeth with visible translucency and enough thickness get lithium disilicate. Anterior teeth that need strength get layered zirconia with a cut-back.
When the margin is subgingival and the bonding isolation is questionable, we move towards zirconia because it can be cemented with a self-adhesive resin rather than requiring perfect isolation.
Where the laboratory should push back
If the requested material cannot be produced at the requested thickness, the honest answer is a different material or a different preparation — not a thinner restoration. We raise it before production, with the numbers, because a remake after cementation costs the clinician more than a conversation.
Common questions
Can you mix materials in one case?
Yes, and it is common: zirconia molars with glass-ceramic premolars, provided the shades are matched at the design stage.
Does monolithic zirconia look acceptable anteriorly?
In multilayer blanks with incisal characterisation, for many patients yes. For a high smile line with strong translucency, layered zirconia or glass-ceramic is better.