Dental Materials and Biomaterials Flashcards
7 cards from real AGD 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 Biomaterials flashcards as text
Which optical property of ceramics is most critical for matching the appearance of natural tooth enamel?
Answer: Translucency
Natural enamel is semi-translucent, so ceramic translucency is essential for an esthetic match, allowing light to pass through similarly.
The coefficient of thermal expansion (CTE) mismatch between a ceramic and its underlying metal substructure can cause:
Answer: Ceramic fracture or delamination
CTE mismatch creates thermal stress during firing and intraoral temperature changes, leading to ceramic fracture or delamination from the metal.
Which mechanism primarily accounts for the superior strength of zirconia compared to other dental ceramics?
Answer: Transformation toughening
Zirconia undergoes stress-induced tetragonal-to-monoclinic phase transformation, absorbing crack energy and dramatically increasing fracture toughness.
Galvanic corrosion in the oral cavity is most likely to occur when:
Answer: Dissimilar metals are in contact with saliva
Galvanic corrosion occurs when dissimilar metals with different electrode potentials are in electrical contact through an electrolyte like saliva.
Which component of dental porcelain gives it its characteristic glass-like quality?
Answer: Silica-based glass matrix
The silica-based glass matrix provides translucency and the glass-like optical and physical properties characteristic of dental porcelain.
A patient presents with a failed composite bond after only 6 months. Which material failure mode is most likely if the fracture is cohesive within the adhesive layer?
Answer: Cohesive failure within the adhesive
Cohesive failure within the adhesive layer indicates the adhesive material itself was the weakest link, often due to inadequate thickness or incomplete cure.
Which setting characteristic distinguishes type IV gypsum (die stone) from type II plaster?
Answer: Type IV has lower expansion and higher compressive strength
Type IV die stone requires less water (0.22–0.24 w/p ratio), exhibits minimal setting expansion (34 MPa.