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Dental Biomaterials Flashcards

7 cards from real ADEX 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 Biomaterials flashcards as text

  1. In amalgam, the gamma-2 phase (Sn8Hg) is considered undesirable because it:

    Answer: Is the weakest and most corrosion-prone phase

    The gamma-2 phase is the weakest component of amalgam and is highly susceptible to corrosion, leading to marginal breakdown.

  2. Which initiator-accelerator system is used in chemically activated (self-cured) composite resins?

    Answer: Benzoyl peroxide and tertiary amine

    Self-cured composites use a two-paste system where benzoyl peroxide in one paste reacts with a tertiary amine in the other to initiate polymerization.

  3. The purpose of adding silane coupling agent to composite resin filler particles is to:

    Answer: Bond the inorganic filler to the organic resin matrix

    Silane coupling agents form a chemical bridge between the inorganic glass filler and the organic resin matrix, enhancing composite strength and durability.

  4. What is galvanic corrosion in the oral cavity?

    Answer: Electrochemical degradation occurring when dissimilar metals contact in saliva

    Galvanic corrosion occurs when two dissimilar metals are in electrical contact via saliva, creating a battery-like cell that corrodes the more anodic metal.

  5. Which characteristic distinguishes Type IV gold alloys from Type I gold alloys?

    Answer: Type IV alloys are harder and used for partial denture frameworks

    Type IV gold alloys have the highest hardness and strength among the four types, making them suitable for partial denture frameworks and thin castings requiring durability.

  6. What is the main advantage of using a rubber base (polysulfide) impression material over alginate?

    Answer: It provides greater dimensional accuracy and longer storage stability

    Polysulfide impressions are dimensionally more stable than alginate and can be poured hours after taking the impression, unlike alginate which must be poured immediately.

  7. The Knoop hardness test is used in dentistry to measure:

    Answer: Surface hardness of mineralized tissues and restorative materials

    The Knoop hardness test uses a diamond indenter to measure surface hardness, and is commonly applied to both tooth structure and dental materials to compare resistance to indentation.