Dental Materials Flashcards

Which type of dental material is classified as an irreversible hydrocolloid impression material?

Answer: Alginate

Alginate is an irreversible hydrocolloid because its gelation is a chemical reaction that cannot be reversed by heating.

What is the primary purpose of a cavity liner placed in a deep preparation?

Answer: To provide pulp protection from chemical and thermal irritation

A cavity liner is placed over the pulp to protect it from the chemical and thermal stimuli that restorative materials may transmit.

Which gypsum product has the highest compressive strength and is used for dies?

Answer: Die stone (Type IV)

Type IV die stone (high-strength stone) has the highest compressive strength due to its low water-to-powder ratio, making it ideal for dies.

What is the setting reaction of zinc phosphate cement?

Answer: Acid-base reaction between zinc oxide and phosphoric acid

Zinc phosphate cement sets via an acid-base reaction where phosphoric acid reacts with zinc oxide powder to form zinc phosphate salt.

Which of the following composite filler types provides the best combination of strength and polishability?

Answer: Hybrid composite

Hybrid composites combine large and small filler particles, offering superior strength compared to microfills and better polishability than macrofills.

What is the major advantage of glass ionomer cement over zinc phosphate cement?

Answer: Chemical adhesion to tooth structure and fluoride release

Glass ionomer cement chemically bonds to enamel and dentin and releases fluoride, providing cariostatic benefits that zinc phosphate lacks.

Which component of dental amalgam is primarily responsible for its corrosion resistance?

Answer: Copper

High copper content in modern amalgam alloys reduces the formation of the corrosion-prone gamma-2 phase (Sn8Hg), improving corrosion resistance.