Dental Materials & Technology Flashcards
7 cards from real AGD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Dental Materials & Technology flashcards as text
Which surface treatment is required before bonding resin cement to a lithium disilicate ceramic restoration?
Answer: Hydrofluoric acid etching followed by silane application
HF acid etches the glassy matrix of lithium disilicate creating a microtextured surface; silane then chemically bridges the ceramic to the resin cement.
What does the term 'tack cure' describe in the placement of resin composite?
Answer: Brief light exposure to partially polymerize and stabilize material for contouring before final cure
A tack cure (2–3 seconds) creates enough polymerization to hold the composite shape during contouring while allowing further manipulation before the final full cure.
Which thermoplastic polymer is most commonly used for clear aligner fabrication?
Answer: Polyethylene terephthalate glycol (PETG)
PETG offers the combination of clarity, stiffness, and thermoformability needed for accurate aligner fabrication with good force delivery characteristics.
A patient's amalgam restoration shows a bluish-gray discoloration of adjacent tooth structure. What is the most likely cause?
Answer: Corrosion products from amalgam diffusing into dentinal tubules
Corrosion byproducts (sulfides and oxides) from dental amalgam diffuse into dentinal tubules over time, causing the characteristic 'amalgam tattoo' effect in tooth structure.
What is the recommended storage condition for vinyl polysiloxane (VPS) impression materials to preserve accuracy?
Answer: Store at room temperature away from heat and latex gloves
VPS should be stored at room temperature; refrigeration slows setting but latex contamination from gloves irreversibly inhibits polymerization at the surface.
What property makes polyether impression materials particularly advantageous in patients with copious saliva?
Answer: They are inherently hydrophilic and set accurately in the presence of moisture
Polyether's hydrophilic nature allows it to displace moisture from tooth surfaces and achieve accurate impressions even in a wet field.
Which parameter of light-curing units (LCUs) most directly determines the rate of photoinitiator activation in resin composites?
Answer: Irradiance (intensity) measured in mW/cm²
Irradiance (mW/cm²) determines the number of photons delivered per unit area per second, which directly controls the rate of camphorquinone or alternative photoinitiator activation.