AGD Dental Materials & Technology 3

Question 1

What is the clinical significance of the gel phase during alginate setting?

Accepted Answer

Optimal time to remove impression from mouth

Answer

The gel phase marks when the alginate has set sufficiently for removal — too early causes tearing, too late risks distortion.

Question 2

Which alloy composition is classified as a high-noble metal alloy per ADA specifications?

Accepted Answer

≥60% noble metal with ≥40% gold

Answer

ADA defines high-noble alloys as containing ≥60% noble metals (gold, platinum, palladium) by weight with ≥40% gold specifically.

Question 3

Which property of composite resin is most responsible for postoperative sensitivity?

Accepted Answer

Polymerization shrinkage stress

Answer

Polymerization shrinkage creates contraction stress at the tooth-composite interface, disrupting the bond and allowing fluid movement in dentinal tubules.

Question 4

What distinguishes Type IV gypsum (die stone) from Type III gypsum (dental stone)?

Accepted Answer

Lower water-to-powder ratio and higher compressive strength

Answer

Type IV die stone requires less water and yields compressive strengths exceeding 34 MPa, making it suitable for accurate die fabrication.

Question 5

In CAD/CAM dentistry, what is the purpose of the sintering step for zirconia restorations?

Accepted Answer

Converting pre-sintered partially stabilized zirconia to full density and strength

Answer

Sintering at 1450–1600°C drives densification of zirconia particles, increasing strength from ~100 MPa to over 900 MPa.

(AGD) Academy of General Dentistry Certification Practice Test

(AGD) Academy of General Dentistry Certification Practice Test

AGD Dental Materials & Technology 3