Practice Test Geeks(NDAEB) National Dental Assisting Examination Board Practice Test
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Dental Materials and Equipment Flashcards

7 cards from real NDAEB practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Dental Materials and Equipment flashcards as text

  1. Alginate impression material is classified as which type of impression material?

    Answer: Irreversible hydrocolloid

    Alginate is an irreversible hydrocolloid because once it undergoes its chemical setting reaction, it cannot be returned to its original state by heating.

  2. What is the correct storage method for an alginate impression before it can be poured with stone?

    Answer: Wrapped in a damp paper towel sealed in a plastic bag

    Alginate impressions must be wrapped in a damp paper towel and sealed in a bag to prevent syneresis (shrinkage from drying) or imbibition (swelling from absorbing water).

  3. Polyvinyl siloxane (PVS) is classified under which category of impression materials?

    Answer: Elastomeric impression material

    PVS is an addition silicone and belongs to the elastomeric category, meaning it sets to a flexible, rubber-like consistency that allows accurate reproduction of undercuts.

  4. Which type of gypsum product is MOST appropriate for fabricating dies used in crown and bridge construction?

    Answer: Type IV die stone

    Type IV die stone has the highest compressive strength and lowest setting expansion, providing the accuracy and hardness required for crown and bridge die fabrication.

  5. How does increasing the water-to-powder ratio of alginate primarily affect the mix?

    Answer: Lengthens the setting time and produces a thinner mix

    Adding more water to alginate dilutes the reaction, lengthening the setting time and producing a thinner, more fluid consistency that is weaker when set.

  6. Which type of impression tray provides the MOST accurate result when using polyvinyl siloxane material?

    Answer: Custom acrylic tray with PVS adhesive

    A custom acrylic tray creates uniform material thickness of 2–3 mm throughout, minimizes distortion, and with PVS adhesive ensures the material stays seated for maximum accuracy.

  7. Which material is most commonly used today to fabricate a provisional (temporary) crown after tooth preparation?

    Answer: Bis-acrylic composite

    Bis-acrylic composite is the standard material for provisional crowns because it offers good esthetics, adequate strength, easy trimming, and can be made chair-side using a matrix of the pre-op tooth.