CDC Laboratory Techniques & Technology 3

Question 1

During staining and glazing of a monolithic zirconia restoration, what is the critical reason for keeping the glaze layer thin?

Accepted Answer

Thick glaze can chip or delaminate due to CTE mismatch

Answer

A glaze layer that is too thick develops residual stress from coefficient of thermal expansion differences, leading to chipping or delamination.

Question 2

Which technique is used to verify the fit of a ceramic restoration on a refractory die before glazing?

Accepted Answer

Fit-checker silicone or pressure-indicating paste

Answer

Fit-checker silicone or pressure-indicating paste applied inside the restoration reveals high spots and contact areas when seated on the die.

Question 3

An incisal porcelain layer appears grayish-white after firing rather than translucent. The MOST probable cause is:

Accepted Answer

Firing in an air atmosphere instead of vacuum

Answer

Firing translucent porcelain without vacuum traps micro-air bubbles in the glass matrix, scattering light and producing an opaque gray-white appearance.

Question 4

When investing a wax pattern for the lost-wax casting technique, the wax must be:

Accepted Answer

Completely surrounded by investment with adequate thickness

Answer

Adequate investment coverage on all surfaces provides structural strength during burnout and prevents mold cracking under casting pressure.

Question 5

Which property of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) contributes most to its fracture resistance?

Accepted Answer

Transformation toughening mechanism

Answer

Transformation toughening occurs when tensile stress at a crack tip triggers tetragonal-to-monoclinic phase transformation, absorbing energy and stopping crack propagation.

(CDC) Certified Dental Ceramist Practice Test

(CDC) Certified Dental Ceramist Practice Test

CDC Laboratory Techniques & Technology 3