Material Selection & Aesthetic Customization Flashcards
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Read the first 7 Material Selection & Aesthetic Customization flashcards as text
A ceramist is layering a central incisor restoration and wants to replicate incisal halo effect. Which technique best achieves this?
Answer: Building a thin opalescent enamel layer over a translucent incisal ceramic
Opalescent enamel ceramic scatters light differently in transmission vs. reflection, creating the blue-white incisal halo seen in natural teeth.
Which ceramic material's coefficient of thermal expansion (CTE) must most precisely match the underlying metal substrate in a PFM crown?
Answer: Veneering porcelain
CTE mismatch between veneering porcelain and the metal coping causes residual stresses during cooling that can lead to porcelain fracture or crazing.
Which modifier is typically added to veneering porcelain to simulate the orange-brown cervical staining seen in older patients?
Answer: Ochre or sienna characterization stain
Ochre and sienna stains replicate the warm orange-brown cervical tones resulting from dentin exposure and extrinsic staining in aging teeth.
When fabricating a ceramic restoration for a patient with a very high lip line (gummy smile), which aesthetic element becomes most critical?
Answer: Cervical emergence profile and gingival integration
A high lip line exposes the cervical region and gingival margins, making emergence profile and color blending at the gingival margin paramount.
Pressed ceramics (e.g., IPS e.max Press) achieve their strength primarily through which microstructural feature?
Answer: Lithium disilicate crystal reinforcement within glass matrix
IPS e.max Press derives its high flexural strength (~400 MPa) from lithium disilicate crystals interlocked within the glass matrix.
Which optical phenomenon should a ceramist exploit to make a short clinical crown appear longer?
Answer: Creating a lighter value at the cervical and gradual darkening toward the incisal
A cervical-to-incisal value gradient (lighter cervical, darker incisal) creates an illusion of greater vertical length by mimicking natural depth perspective.
In ceramic material selection, which property describes a material's resistance to crack propagation, most critical for long-span bridges?
Answer: Fracture toughness (KIC)
Fracture toughness (KIC) measures resistance to crack propagation and is the defining property for long-span ceramic bridge frameworks under cyclic loading.