AGD Dental Materials and Application 4

Question 1

The modulus of elasticity of a restorative material is clinically important because it describes:

Accepted Answer

The stiffness of the material under load

Answer

The modulus of elasticity (Young's modulus) quantifies stiffness — a high modulus means the material resists elastic deformation, which is critical for load-bearing restorations.

Question 2

When using a total-etch adhesive technique, what is the critical risk of over-drying the dentin after acid etching?

Accepted Answer

Collagen fiber collapse prevents adhesive infiltration and reduces bond strength

Answer

Over-drying demineralized dentin causes collagen network collapse, blocking adhesive monomer infiltration and dramatically reducing dentin bond strength.

Question 3

Which type of zirconia is used in monolithic posterior crowns and valued for its high strength?

Accepted Answer

Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP)

Answer

Y-TZP zirconia has flexural strength of 900–1200 MPa due to transformation toughening, making it the strongest ceramic for monolithic posterior crowns.

Question 4

What is the purpose of the oxygen inhibition layer that forms on the surface of light-cured composites?

Accepted Answer

It allows chemical bonding to the next increment of composite

Answer

The oxygen-inhibited layer contains unreacted monomers that allow subsequent increments or surface sealers to chemically bond, ensuring interlaminar adhesion.

Question 5

A gold alloy classified as Type IV (extra hard) would most appropriately be used for:

Accepted Answer

Thin-gauge clasps for removable partial dentures and long-span bridges

Answer

Type IV gold alloys have the highest hardness and yield strength, making them suitable for thin sections under high stress such as clasps and long-span bridge frameworks.

(AGD) Academy of General Dentistry Certification Practice Test

(AGD) Academy of General Dentistry Certification Practice Test

AGD Dental Materials and Application 4