Dental Materials and Application 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 Application flashcards as text
Which mechanism is responsible for the self-adhesive property of glass ionomer cement to tooth structure?
Answer: Chelation of polyacrylic acid with calcium in hydroxyapatite
GIC bonds chemically via chelation between the carboxylate groups of polyacrylic acid and calcium ions in hydroxyapatite, requiring no separate etching step.
What is the working time of a dental material most directly influenced by?
Answer: The operator's mixing technique and temperature
Working time is primarily affected by mixing technique (spatulation rate/area) and ambient temperature — higher temperatures accelerate the reaction and shorten working time.
A flowable composite would be preferred over a packable composite in which clinical situation?
Answer: Lining the internal walls of a deep Class I preparation
Flowable composites are ideal as liners in cavity preparations due to their low viscosity, easy adaptation, and elastic modulus that provides a stress-absorbing layer.
Galvanic corrosion in the mouth is most likely to occur when:
Answer: Dissimilar metals contact each other in the presence of saliva
Galvanic corrosion results from electrochemical reactions between dissimilar metals connected through an electrolyte such as saliva, generating a small electric current.
Which cement is contraindicated as a final luting agent for porcelain-fused-to-metal crowns due to its high acidity?
Answer: Zinc phosphate cement
Zinc phosphate cement's initial low pH (~2) can cause transient pulpal inflammation and is generally considered less biocompatible than newer cements for final cementation.
What is the primary reason for applying a dentin bonding agent in multiple coats?
Answer: To reduce the concentration of solvents and ensure complete monomer coverage
Multiple coats ensure complete surface coverage, reduce residual solvent through evaporation, and build a sufficient thickness of adhesive for optimal bonding.
Which impression material exhibits the highest tear strength, making it well-suited for recording deep undercuts?
Answer: Polysulfide rubber
Polysulfide rubber (mercaptan) has the highest tear strength among elastomeric impressions, allowing withdrawal from deep undercuts without tearing.