Restorative and Impression Materials Flashcards
6 cards from real RDA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Restorative and Impression Materials flashcards as text
Which type of alginate impression material error results in a grainy or rough surface texture on the model?
Answer: Insufficient mixing time resulting in unmixed alginate particles
Insufficient mixing (undermixing) leaves unmixed alginate particles that produce a grainy, rough texture on the surface of the poured model.
What is the purpose of a cavity liner (e.g., calcium hydroxide) in a deep cavity preparation?
Answer: To stimulate secondary (reparative) dentin formation and protect the pulp from thermal and chemical irritation
Calcium hydroxide (Ca(OH)2) liners stimulate reparative (tertiary/secondary) dentin formation through their high pH, and provide a protective layer between the restorative material and the pulp.
What is the difference between a base and a liner in restorative dentistry?
Answer: A liner is a thin coating for pulp protection; a base is a thick layer providing pulp protection AND structural support beneath a restoration
A liner is a thin (0.5 mm) coating applied to the deepest portions of the preparation for pulp protection (chemical/biological). A base is a thicker (1–2 mm) material providing both thermal insulation and structural support, replacing missing dentin.
What is the recommended action if a polyvinyl siloxane (PVS) impression is contaminated with saliva before setting?
Answer: Discard the impression and retake it — saliva contamination ruins PVS accuracy
PVS impression materials are hydrophobic. Saliva or moisture contamination before or during setting compromises surface detail reproduction and dimensional accuracy, requiring the impression to be discarded and retaken.
Which composite resin curing light parameter is most important for adequate depth of cure?
Answer: Irradiance (intensity) in mW/cm² and exposure time
The irradiance (light intensity in mW/cm²) and exposure time together determine the energy dose delivered to the composite. Adequate intensity and sufficient time are critical for achieving proper depth of cure and mechanical properties.
What is the primary advantage of glass ionomer cement over composite resin for cervical restorations?
Answer: Chemical adhesion to tooth structure and fluoride release for caries prevention
Glass ionomer cements chemically bond to enamel and dentin (no acid etch required) and continuously release fluoride ions, which inhibit secondary caries — a major advantage for cervical lesions near the gingiva.