DMD Dental Materials Science 2

Question 1

Which ADA Type of gypsum product has the highest compressive strength and is most suitable for fabricating dental dies?

Accepted Answer

Type IV — Die stone

Answer

Type IV die stone (high-strength dental stone) has the highest compressive strength due to its low water-to-powder ratio and is the preferred material for accurate dies.

Question 2

The elastic modulus (Young's modulus) of a dental material represents:

Accepted Answer

The ratio of stress to strain within the elastic range

Answer

Young's modulus equals stress divided by strain within the elastic (proportional) range, and it quantifies the stiffness or rigidity of a material.

Question 3

Glass ionomer cement achieves adhesion to tooth structure primarily through which mechanism?

Accepted Answer

Chemical ionic bonding with calcium in hydroxyapatite

Answer

Glass ionomer cement bonds chemically through exchange of ions between the polyalkenoic acid and calcium ions in the hydroxyapatite of tooth structure.

Question 4

What is the primary clinical significance of fluoride release from glass ionomer cements?

Accepted Answer

Provides secondary anticariogenic protection at restoration margins

Answer

Fluoride released from glass ionomer cements inhibits bacterial metabolism and promotes remineralization, providing secondary caries prevention at the margins.

Question 5

In porcelain-fused-to-metal (PFM) restorations, which type of ceramic is layered directly onto the metal coping?

Accepted Answer

Feldspathic porcelain

Answer

Feldspathic porcelain is used in PFM restorations because its thermal expansion coefficient is compatible with dental metal alloys, ensuring a durable bond.

DMD - Doctor of Dental Medicine Practice Test

DMD - Doctor of Dental Medicine Practice Test

DMD Dental Materials Science 2