NBDHE Dental Materials and Procedures 3

Question 1

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

Accepted Answer

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

Answer

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.

Question 2

Zinc phosphate cement is best characterized as:

Accepted Answer

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

Answer

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.

Question 3

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

Accepted Answer

Amalgam condenser (plugger)

Answer

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.

Question 4

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

Accepted Answer

Oxidative discoloration of resin matrix and water sorption

Answer

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.

Question 5

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

Accepted Answer

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

Answer

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.

NBDHE Test Practice Test

NBDHE Test Practice Test

NBDHE Dental Materials and Procedures 3