Dental Materials and Procedures Flashcards

What is the primary advantage of resin-modified glass ionomer (RMGI) over conventional glass ionomer cement?

Answer: Improved physical properties and command set via light curing while retaining fluoride release

RMGI incorporates HEMA and a light-curing component to allow command set, improving handling and physical properties while retaining the fluoride release and chemical adhesion of conventional GIC.

Zinc phosphate cement is best characterized as:

Answer: A cement with high compressive strength and low tensile strength, requiring pulpal protection due to initial acidity

Zinc phosphate cement has excellent compressive strength but low tensile strength. Its freshly mixed material has a pH of ~3.5, which requires a cavity liner/base for pulp protection in deep preparations.

Which instrument is used to condense amalgam into a prepared cavity?

Answer: Amalgam condenser (plugger)

Amalgam condensers (pluggers) are used to firmly adapt amalgam increments to the cavity walls and floor, eliminating voids and adapting the material to line angles.

The color stability of composite resins is primarily affected by which process over time?

Answer: Oxidative discoloration of resin matrix and water sorption

Composite resins undergo color change primarily due to oxidation of the organic resin matrix and water sorption, which causes swelling and softening and can trap extrinsic stains.

When taking an elastomeric impression, the tray adhesive should be applied:

Answer: At least 15 minutes before taking the impression to allow it to dry completely

Tray adhesive for elastomeric impressions must dry for at least 15 minutes to form a tacky film that chemically bonds to the impression material and prevents separation from the tray.

What is the function of eugenol in zinc oxide eugenol (ZOE) impression paste and temporary cements?

Answer: It acts as the liquid component that reacts with zinc oxide to form a chelate, providing obtundent (sedative) effects

Eugenol reacts with zinc oxide to form zinc eugenolate (a chelate), and it also has obtundent (pulp-sedating) and antibacterial properties beneficial for temporary restorations.