NBDE Restorative Dentistry Questions and Answers

Question 1

In high-copper dental amalgams, what is the primary function of the increased copper content?

Accepted Answer

To reduce corrosion potential by eliminating the Gamma-2 (Sn-Hg) phase.

Answer

To increase the setting expansion of the material.

Answer

To improve the esthetics and polishability of the final restoration.

Answer

To decrease the compressive strength of the set amalgam.

Question 2

Which component of dental composite resin is responsible for chemically bonding the inorganic filler particles to the organic resin matrix?

Accepted Answer

Silane coupling agent

Answer

Initiator (e.g., camphorquinone)

Answer

Resin matrix (e.g., Bis-GMA)

Answer

Inhibitor (e.g., BHT)

Question 3

A clinician is preparing a Class II cavity for an amalgam restoration on a mandibular molar. To ensure adequate resistance form, which of the following design features is most important?

Accepted Answer

A flat pulpal floor perpendicular to the long axis of the tooth.

Answer

Convergent buccal and lingual walls.

Answer

Beveling the axiopulpal line angle.

Answer

Ensuring the isthmus width is less than one-fourth the intercuspal distance.

Question 4

When preparing a tooth for a composite restoration, what is the primary purpose of applying 30-40% phosphoric acid to the enamel surface?

Accepted Answer

To remove the smear layer and create microporosities for micromechanical retention.

Answer

To disinfect the prepared cavity surface.

Answer

To chemically activate the primer in the bonding agent.

Answer

To expose collagen fibrils for hybridization in the enamel.

Question 5

A pediatric patient with high caries risk requires a restoration on a newly erupted first permanent molar where complete moisture control is difficult. Which of the following materials is most indicated due to its unique chemical properties?

Accepted Answer

Resin-modified glass ionomer (RMGI)

Answer

Packable composite resin

Answer

Dental amalgam

Answer

Ceramic inlay

Question 6

For a tooth that has undergone endodontic treatment and requires a full coverage crown, what is the primary purpose of ensuring a 1.5 to 2.0 mm ferrule?

Accepted Answer

To resist functional lever forces and protect the tooth from vertical fracture.

Answer

To provide adequate retention for the temporary crown.

Answer

To create a friction-locked seal at the crown margin.

Answer

To improve the esthetics of the final restoration by hiding the margin.