Laboratory Techniques & Technology Flashcards
7 cards from real CDC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Laboratory Techniques & Technology flashcards as text
During staining and glazing of a monolithic zirconia restoration, what is the critical reason for keeping the glaze layer thin?
Answer: Thick glaze can chip or delaminate due to CTE mismatch
A glaze layer that is too thick develops residual stress from coefficient of thermal expansion differences, leading to chipping or delamination.
Which technique is used to verify the fit of a ceramic restoration on a refractory die before glazing?
Answer: Fit-checker silicone or pressure-indicating paste
Fit-checker silicone or pressure-indicating paste applied inside the restoration reveals high spots and contact areas when seated on the die.
An incisal porcelain layer appears grayish-white after firing rather than translucent. The MOST probable cause is:
Answer: Firing in an air atmosphere instead of vacuum
Firing translucent porcelain without vacuum traps micro-air bubbles in the glass matrix, scattering light and producing an opaque gray-white appearance.
When investing a wax pattern for the lost-wax casting technique, the wax must be:
Answer: Completely surrounded by investment with adequate thickness
Adequate investment coverage on all surfaces provides structural strength during burnout and prevents mold cracking under casting pressure.
Which property of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) contributes most to its fracture resistance?
Answer: Transformation toughening mechanism
Transformation toughening occurs when tensile stress at a crack tip triggers tetragonal-to-monoclinic phase transformation, absorbing energy and stopping crack propagation.
In CAD software for dental restorations, the 'emergence profile' tool is primarily used to:
Answer: Define the contour of the restoration from the gingival margin to the height of contour
The emergence profile shapes how the restoration transitions from the subgingival finish line to its widest point, critical for gingival health and esthetics.
A ceramist adds a fluorescent modifier to a ceramic build-up. What effect does this achieve in natural lighting?
Answer: Imparts a lifelike warm glow matching natural tooth fluorescence
Fluorescent modifiers absorb ultraviolet light and re-emit it as visible blue-white light, replicating the natural fluorescence of tooth structure.