CDT CDT Ceramics & Porcelain Techniques

Question 1

What is the primary purpose of applying an opaque layer in a porcelain-fused-to-metal (PFM) restoration?

Accepted Answer

To mask the metal substrate and establish base shade

Answer

To add translucency to the final restoration

Answer

To strengthen the porcelain build-up

Answer

To improve marginal fit of the crown

Question 2

Which firing stage in porcelain condensation produces the greatest shrinkage?

Accepted Answer

Body/dentin firing

Answer

Glaze firing

Answer

Opaque firing

Answer

Wash bake

Question 3

What does a 'wash bake' accomplish in ceramic fabrication?

Accepted Answer

Applies a thin porcelain wash to correct minor shade discrepancies

Answer

Removes excess wax from a ceramic coping

Answer

Initiates the sintering of zirconia

Answer

Bonds the ceramic to metal with a bonding agent

Question 4

What causes a 'chipping' or delamination failure in a PFM restoration?

Accepted Answer

Using high-fusing porcelain on a low-fusing alloy

Answer

Excessive metal thickness

Answer

Inadequate bond between opaque and body porcelain

Answer

Over-glazing the surface

Question 5

Which technique is used to characterize the internal structure of a ceramic crown for a more lifelike appearance?

Accepted Answer

Layering technique with dentin, enamel, and effect powders

Answer

Single-layer pressing and staining only

Answer

Glazing with a tinted glaze paste

Answer

Sandblasting with alumina oxide

Question 6

What is the coefficient of thermal expansion (CTE), and why is it critical in PFM restorations?

Accepted Answer

A measure of how a material expands/contracts with temperature; metal and ceramic CTEs must be compatible

Answer

The rate at which porcelain sets; it determines firing time

Answer

The strength rating of dental porcelain; higher is better

Answer

A measure of porcelain translucency used to select shade